Littérature scientifique sur le sujet « Graded manifold »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Graded manifold ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Graded manifold"
1
Sardanashvily, G., et W. Wachowski. « Differential Calculus onN-Graded Manifolds ». Journal of Mathematics 2017 (2017) : 1–19. http://dx.doi.org/10.1155/2017/8271562.
Texte intégralRésumé :
The differential calculus, including formalism of linear differential operators and the Chevalley–Eilenberg differential calculus, overN-graded commutative rings and onN-graded manifolds is developed. This is a straightforward generalization of the conventional differential calculus over commutative rings and also is the case of the differential calculus over Grassmann algebras and onZ2-graded manifolds. We follow the notion of anN-graded manifold as a local-ringed space whose body is a smooth manifoldZ. A key point is that the graded derivation module of the structure ring of graded functions on anN-graded manifold is the structure ring of global sections of a certain smooth vector bundle over its bodyZ. Accordingly, the Chevalley–Eilenberg differential calculus on anN-graded manifold provides it with the de Rham complex of graded differential forms. This fact enables us to extend the differential calculus onN-graded manifolds to formalism of nonlinear differential operators, by analogy with that on smooth manifolds, in terms of graded jet manifolds ofN-graded bundles.
2
Ševera, Pavol, et Michal Širaň. « Integration of Differential Graded Manifolds ». International Mathematics Research Notices 2020, no 20 (15 février 2019) : 6769–814. http://dx.doi.org/10.1093/imrn/rnz004.
Texte intégralRésumé :
Abstract We consider the problem of integration of $L_\infty $-algebroids (differential non-negatively graded manifolds) to $L_\infty $-groupoids. We first construct a “big” Kan simplicial manifold (Fréchet or Banach) whose points are solutions of a (generalized) Maurer–Cartan equation. The main analytic trick in our work is an integral transformation sending the solutions of the Maurer–Cartan equation to closed differential forms. Following the ideas of Ezra Getzler, we then impose a gauge condition that cuts out a finite-dimensional simplicial submanifold. This “smaller” simplicial manifold is (the nerve of) a local Lie $\ell $-groupoid. The gauge condition can be imposed only locally in the base of the $L_\infty $-algebroid; the resulting local $\ell $-groupoids glue up to a coherent homotopy, that is, we get a homotopy coherent diagram from the nerve of a good cover of the base to the (simplicial) category of local $\ell $-groupoids. Finally, we show that a $k$-symplectic differential non-negatively graded manifold integrates to a local $k$-symplectic Lie $\ell$-groupoid; globally, these assemble to form an $A_\infty$-functor. As a particular case for $k=2$, we obtain integration of Courant algebroids.
3
Bruce, Andrew James, et Janusz Grabowski. « Riemannian Structures on Z 2 n -Manifolds ». Mathematics 8, no 9 (1 septembre 2020) : 1469. http://dx.doi.org/10.3390/math8091469.
Texte intégralRésumé :
Very loosely, Z2n-manifolds are ‘manifolds’ with Z2n-graded coordinates and their sign rule is determined by the scalar product of their Z2n-degrees. A little more carefully, such objects can be understood within a sheaf-theoretical framework, just as supermanifolds can, but with subtle differences. In this paper, we examine the notion of a Riemannian Z2n-manifold, i.e., a Z2n-manifold equipped with a Riemannian metric that may carry non-zero Z2n-degree. We show that the basic notions and tenets of Riemannian geometry directly generalize to the setting of Z2n-geometry. For example, the Fundamental Theorem holds in this higher graded setting. We point out the similarities and differences with Riemannian supergeometry.
4
De Nicola, Antonio, et Ivan Yudin. « Generalized Goldberg Formula ». Canadian Mathematical Bulletin 59, no 3 (1 septembre 2016) : 508–20. http://dx.doi.org/10.4153/cmb-2016-007-4.
Texte intégralRésumé :
AbstractIn this paper we prove a useful formula for the graded commutator of the Hodge codifferential with the left wedge multiplication by a fixed p-form acting on the de Rham algebra of a Riemannian manifold. Our formula generalizes a formula stated by Samuel I. Goldberg for the case of 1-forms. As first examples of application we obtain new identities on locally conformally Kähler manifolds and quasi-Sasakian manifolds. Moreover, we prove that under suitable conditions a certain subalgebra of differential forms in a compact manifold is quasi-isomorphic as a CDGA to the full de Rham algebra.
5
Kotov, Alexei, et Thomas Strobl. « Characteristic classes associated to Q-bundles ». International Journal of Geometric Methods in Modern Physics 12, no 01 (28 décembre 2014) : 1550006. http://dx.doi.org/10.1142/s0219887815500061.
Texte intégralRésumé :
A Q-manifold is a graded manifold endowed with a vector field of degree 1 squaring to zero. We consider the notion of a Q-bundle, that is, a fiber bundle in the category of Q-manifolds. To each homotopy class of "gauge fields" (sections in the category of graded manifolds) and each cohomology class of a certain subcomplex of forms on the fiber we associate a cohomology class on the base. As any principal bundle yields canonically a Q-bundle, this construction generalizes Chern–Weil classes. Novel examples include cohomology classes that are locally de Rham differential of the integrands of topological sigma models obtained by the AKSZ-formalism in arbitrary dimensions. For Hamiltonian Poisson fibrations one obtains a characteristic 3-class in this manner. We also relate the framework to equivariant cohomology and Lecomte's characteristic classes of exact sequences of Lie algebras.
6
Tahora, Saraban, et Khondokar M. Ahmed. « Study on De Rham Cohomology Algebra of Manifolds ». Dhaka University Journal of Science 64, no 2 (31 juillet 2016) : 109–13. http://dx.doi.org/10.3329/dujs.v64i2.54484.
Texte intégralRésumé :
In the present paper some aspects of exterior derivative, graded algebra, cohomology algebra, de Rham cohomology algebra, singular homology, cohomology class are studied. Graded subspace, smooth map, a singular P- - simplex in a manifold M, oriented n- manifold M, the space of P- cycles and P- boundaries, Pth singular homology and homology class are treated in our paper. A theorem 3.03 is established which is related to orientable manifold.
Dhaka Univ. J. Sci. 64(2): 109-113, 2016 (July)
7
GILLE, CATHERINE. « ON THE LE-MURAKAMI-OHTSUKI INVARIANT IN DEGREE 2 FOR SEVERAL CLASSES OF 3-MANIFOLDS ». Journal of Knot Theory and Its Ramifications 12, no 01 (février 2003) : 17–45. http://dx.doi.org/10.1142/s0218216503002287.
Texte intégralRésumé :
The 3-manifolds invariant of Le, Murakami and Ohtsuki is the universal finite type invariant for integral homology spheres. It takes values in the graded algebra of trivalent graphs and it is known that its degree one part is essentially the Casson-Walker-Lescop invariant. Here we compute the degree two term for several classes of 3-manifolds. In particular, we give an expression of ω (ML) up to order 2 when MLis the 3-manifold obtained by Dehn surgery along a framed link L with one or two components.
8
IKEDA, NORIAKI, et KOZO KOIZUMI. « CURRENT ALGEBRAS AND QP-MANIFOLDS ». International Journal of Geometric Methods in Modern Physics 10, no 06 (30 avril 2013) : 1350024. http://dx.doi.org/10.1142/s0219887813500242.
Texte intégralRésumé :
Generalized current algebras introduced by Alekseev and Strobl in two dimensions are reconstructed by a graded manifold and a graded Poisson brackets. We generalize their current algebras to higher dimensions. QP-manifolds provide the unified structures of current algebras in any dimension. Current algebras give rise to structures of Leibniz/Loday algebroids, which are characterized by QP-structures. Especially, in three dimensions, a current algebra has a structure of a Lie algebroid up to homotopy introduced by Uchino and one of the authors, which has a bracket of a generalization of the Courant–Dorfman bracket. Anomaly cancellation conditions are reinterpreted as generalizations of the Dirac structure.
9
Paepe, Karl De. « Graded subalgebras of the Lie algebra of a smooth manifold ». International Journal of Mathematics and Mathematical Sciences 27, no 3 (2001) : 141–48. http://dx.doi.org/10.1155/s0161171201010511.
Texte intégral
10
Gualtieri, Marco, Mykola Matviichuk et Geoffrey Scott. « Deformation of Dirac Structures via L∞ Algebras ». International Mathematics Research Notices 2020, no 14 (22 juin 2018) : 4295–323. http://dx.doi.org/10.1093/imrn/rny134.
Texte intégralRésumé :
Abstract The deformation theory of a Dirac structure is controlled by a differential graded Lie algebra that depends on the choice of an auxiliary transversal Dirac structure; if the transversal is not involutive, one obtains an $L_\infty $ algebra instead. We develop a simplified method for describing this $L_\infty $ algebra and use it to prove that the $L_\infty $ algebras corresponding to different transversals are canonically $L_\infty $–isomorphic. In some cases, this isomorphism provides a formality map, as we show in several examples including (quasi)-Poisson geometry, Dirac structures on Lie groups, and Lie bialgebras. Finally, we apply our result to a classical problem in the deformation theory of complex manifolds; we provide explicit formulas for the Kodaira–Spencer deformation complex of a fixed small deformation of a complex manifold, in terms of the deformation complex of the original manifold.
Thèses sur le sujet "Graded manifold"
1
Hogle, Eric. « RO(C2)-graded Cohomology of Equivariant Grassmannian Manifolds ». Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23735.
Texte intégral
2
Lavau, Sylvain. « Lie infini-algébroides et feuilletages singuliers ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1215/document.
Texte intégralRésumé :
On dit qu'une variété est feuilletée lorsqu'il existe une partition de celle-ci en sous-variétés immergées. La théorie des feuilletages a des applications très profondes dans divers champs des Mathématiques et de la Physique, et il semble d'autant plus intéressant de pouvoir analyser le feuilletage à partir de ce qui semble être une donnée plus fondamentale : sa distribution de champs de vecteurs associée. C'est ainsi que nous avons observé que si le feuilletage est résolu par un fibré gradué, on peut relever le crochet de Lie des champs de vecteurs en une structure de Lie infini-algébroide sur ce fibré. D'autre part, cette structure est universelle dans le sens où toute autre résolution du feuilletage sera isomorphe à celle-ci dans un sens L_infini, mais seulement à homotopie près. Lorsqu'on se limite à l'étude au dessus d'un point, on observe que la cohomologie associée à la résolution devient potentiellement non triviale. La structure de Lie infini-algébroide universelle se réduit alors à une algèbre de Lie graduée sur cette cohomologie. Cette structure algébrique peut être transportée (non canoniquement) tout le long de la feuille, transformant la cohomologie au dessus d'une feuille en algébroide de Lie gradué. Cela nous permet de retrouver des résultats déjà connus par ailleurs et de déduire des avancées prometteusesA smooth manifold is said to be foliated when it is partitioned into immersed submanifolds. Foliation Theory has profound applications in various fields of Mathematics and Physics, and it seems much more interesting to analyze the foliation from what seems to be a more fundamental point of view: its associated distribution of vector fields. Thus we have noticed that if the foliation is resolved by a graded fiber bundle, one can lift the Lie bracket of vector fields into a Lie infinity-algebroid structure on this fiber bundle. Moreover, this structure is universal in the sense that any other resolution of the foliation is isomorphic to it in the L_infinity setup, but only up to homotopy. When one restricts the analysis over a point, we observe that the cohomology associated to the resolution may become non trivial. The universal Lie infinity-algebroid structure hence reduces to a graded Lie algebra structure on this cohomology. This algebraic structure can be carried (non canonically) along the leaf, providing the cohomology over a leaf with a graded Lie algebroid structure. This enables us to retrieve former well-known results, as well as promising advances
3
García-Zelada, David. « Aspects géométriques et probabilistes des gaz de coulomb Concentration for Coulomb gases on compact manifolds A large deviation principle for empirical measures on Polish spaces : Application to singular Gibbs measures on manifolds Extremal particles of two-dimensional Coulomb gases and random polynomials on a positive background Edge fluctuations for a class of two-dimensional determinantal Coulomb gases ». Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLED046.
Texte intégralRésumé :
Nous explorons des modèles probabilistes appelés gaz de Coulomb. Ils apparaissent dans différents contextes comme par exemple dans la théorie des matrices aléatoires, l'effet Hall quantique fractionnaire de Laughlin et les modèles de supraconductivité de Ginzburg-Landau. Dans le but de mieux comprendre le rôle de l'espace ambiant, nous étudions des versions géométriques de ce système. Nous exploitons trois structures sur ce modèle. La première est définie par la interaction électrostatique provenant de la loi de Gauss. La deuxième est la structure déterminantale disponible que pour des valeurs précises de la température. La troisième est le principe de minimisation de l'énergie libre en physique, qui permet étudier des modèles plus généraux. Ces travaux conduisent à des nombreux questions ouvertes et à une famille de modèles d'intérêtWe explore probabilistic models usually called Coulomb gases. They arise naturally in mathematics and physics. We can mention random matrix theory, the Laughlin fractional quantum Hall effect and the Ginzburg-Landau systems of superconductivity. In order to better understand the role of the ambient space, we study geometric versions of such systems. We exploit three structures. The first one comes from the electrostatic nature of the interaction given by Gauss's law. The second one is the determinantal structure which appears only for a specific temperature. The third one is the minimization of the free energy principle, coming from physics which gives us a tool to understand more general models. This work leads to many open questions on a whole family of models which can be of independent interest.)
4
Seltz, Andréa. « Application of deep learning to turbulent combustion modeling of real jet fuel for the numerical prediction of particulate emissions Direct mapping from LES resolved scales to filtered-flame generated manifolds using convolutional neural networks Solving the population balance equation for non-inertial particles dynamics using probability density function and neural networks : application to a sooting flame ». Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR08.
Texte intégralRésumé :
Face à l'urgence climatique, l’efficacité énergétique et la réduction des émissions polluantes est devenue une priorité pour l'industrie aéronautique. La précision de la modélisation des phénomènes physicochimiques joue un rôle critique dans qualité de la prédiction des émissions de suie et des gaz à effet de serre par les chambres de combustion. Dans ce contexte, des méthodes d’apprentissage profond sont utilisées pour construire des modélisations avancées des émissions de particules. Une méthode automatisée de réduction et d’optimisation de la cinétique chimique d’un combustible aéronautique réel est dans un premier temps appliquée à la simulation aux grandes échelles pour la prédiction des émissions de monoxyde de carbone. Ensuite, des réseaux de neurones sont entraînés pour simuler le comportement dynamique des suies dans la chambre de combustion et prédire la distribution de taille des particules émisesWith the climate change emergency, pollutant and fuel consumption reductions are now a priority for aircraft industries. In combustion chambers, the chemistry and soot modeling are critical to correctly quantify engines soot particles and greenhouse gases emissions. This thesis aimed at improving aircraft numerical pollutant tools, in terms of computational cost and prediction level, for engines high fidelity simulations. It was achieved by enhancing chemistry reduction tools, allowing to predict CO emissions of an aircraft engines at affordable cost for the industry. Next, a novel closure model for unresolved terms in the LES filtered transport equations is developed, based on neural networks (NN), to propose a better flame modeling. Then, an original soot model for engine high fidelity simulations is presented, also based on NN. This new model is applied to a one-dimensional premixed sooted flame, and finally to an industrial combustion chamber LES with measured soot comparison
5
Kervazo, Christophe. « Optimization framework for large-scale sparse blind source separation ». Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS354/document.
Texte intégralRésumé :
Lors des dernières décennies, la Séparation Aveugle de Sources (BSS) est devenue un outil de premier plan pour le traitement de données multi-valuées. L’objectif de ce doctorat est cependant d’étudier les cas grande échelle, pour lesquels la plupart des algorithmes classiques obtiennent des performances dégradées. Ce document s’articule en quatre parties, traitant chacune un aspect du problème: i) l’introduction d’algorithmes robustes de BSS parcimonieuse ne nécessitant qu’un seul lancement (malgré un choix d’hyper-paramètres délicat) et fortement étayés mathématiquement; ii) la proposition d’une méthode permettant de maintenir une haute qualité de séparation malgré un nombre de sources important: iii) la modification d’un algorithme classique de BSS parcimonieuse pour l’application sur des données de grandes tailles; et iv) une extension au problème de BSS parcimonieuse non-linéaire. Les méthodes proposées ont été amplement testées, tant sur données simulées que réalistes, pour démontrer leur qualité. Des interprétations détaillées des résultats sont proposéesDuring the last decades, Blind Source Separation (BSS) has become a key analysis tool to study multi-valued data. The objective of this thesis is however to focus on large-scale settings, for which most classical algorithms fail. More specifically, it is subdivided into four sub-problems taking their roots around the large-scale sparse BSS issue: i) introduce a mathematically sound robust sparse BSS algorithm which does not require any relaunch (despite a difficult hyper-parameter choice); ii) introduce a method being able to maintain high quality separations even when a large-number of sources needs to be estimated; iii) make a classical sparse BSS algorithm scalable to large-scale datasets; and iv) an extension to the non-linear sparse BSS problem. The methods we propose are extensively tested on both simulated and realistic experiments to demonstrate their quality. In-depth interpretations of the results are proposed
6
Giovannardi, Gianmarco. « Variations for submanifolds of fixed degree ». Doctoral thesis, 2020. https://hdl.handle.net/2158/1287865.
Texte intégralRésumé :
The aim of this PhD thesis is to study the area functional for submanifolds immersed in an equiregular graded manifold. This setting, extends the sub-Riemannian one, removing the bracket generating condition. However, even in the sub-Riemannian setting only sub-manifolds of dimension or codimension one have been extensively studied. We will study the general case and observe that in higher codimension new phenomena arise, which can not show up in the Riemannian case. In particular, we will prove the existence of isolated surfaces, which do not admit degree preserving variation: a phenomena observed by now only for curves, related to the notion of abnormal geodesics.
7
Ewert, Eske Ellen. « Index theory and groupoids for filtered manifolds ». Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-152D-2.
Texte intégral
8
TORTORELLA, ALFONSO GIUSEPPE. « Deformations of coisotropic submanifolds in Jacobi manifolds ». Doctoral thesis, 2017. http://hdl.handle.net/2158/1077777.
Texte intégralRésumé :
In this thesis, we investigate deformation theory and moduli theory of coisotropic submanifolds in Jacobi manifolds. Originally introduced by Kirillov as local Lie algebras with one dimensional fibers, Jacobi manifolds encompass, unifying and generalizing, locally conformal symplectic manifolds, locally conformal Poisson manifolds, and non-necessarily coorientable contact manifolds.
We attach an L-infinity-algebra to any coisotropic submanifold in a Jacobi manifold. Our construction generalizes and unifies analogous constructions by Oh-Park (symplectic case), Cattaneo-Felder (Poisson case), and Le-Oh (locally conformal symplectic case). As a completely new case we also associate an L-infinity-algebra with any coisotropic submanifold in a contact manifold. The L-infinity-algebra of a coisotropic submanifold S controls the formal coisotropic deformation problem of S, even under Hamiltonian equivalence, and provides criteria both for the obstructedness and for the unobstructedness at the formal level. Additionally we prove that if a certain condition ("fiberwise entireness") is satisfied then the L-infinity-algebra controls the non-formal coisotropic deformation problem, even under Hamiltonian equivalence.
We associate a BFV-complex with any coisotropic submanifold in a Jacobi manifold. Our construction extends an analogous construction by Schatz in the Poisson setting, and in particular it also applies in the locally conformal symplectic/Poisson setting and the contact setting. Unlike the L-infinity-algebra, we prove that, with no need of any restrictive hypothesis, the BFV-complex of a coisotropic submanifold S controls the non-formal coisotropic deformation problem of S, even under both Hamiltonian equivalence and Jacobi equivalence.
Notwithstanding the differences there is a close relation between the approaches to the coisotropic deformation problem via L-infinity-algebra and via BFV-complex. Indeed both the L-infinity-algebra and the BFV-complex of a coisotropic submanifold S provide a cohomological reduction of S. Moreover they are L-infinity quasi-isomorphic and so they encode equally well the moduli space of formal coisotropic deformations of S under Hamiltonian equivalence.
In addition we exhibit two examples of coisotropic submanifolds in the contact setting whose coisotropic deformation problem is obstructed at the formal level. Further we provide a conceptual explanation of this phenomenon both in terms of the L-infinity-algebra and in terms of the BFV-complex.
9
Venturello, Lorenzo. « Combinatorial and algebraic properties of balanced simplicial complexes ». Doctoral thesis, 2019. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-201911192203.
Texte intégralRésumé :
Simplicial complexes are mathematical objects whose importance stretches from topology to commutative algebra and combinatorics. In this thesis we focus on the family of balanced simplicial complexes. A d-dimensional simplicial complex is balanced if its 1-skeleton can be properly (d+1)-colored, as in the classical graph theoretic sense. Equivalently, a d-dimensional complex is balanced iff it admits a non-degenerate simplicial projection to the d-simplex. We present results on these complexes from a number of different points of view. After two introductory chapters, we exhibit in chapter 3 an infinite family of balanced counterexamples to Stanley's partitionability conjecture. These complexes, which are in addition constructible, answer a question of Duval et al. in the negative. Next we shift to combinatorial topology, and study cross-flips, i.e., local moves on balanced manifolds introduced by Izmestiev, Klee and Novik, which preserve both the coloring and the topological type. In chapter 4 we provide an explicit description and enumeration of an interesting subset of these moves and use it to prove a Pachner-type theorem. Indeed, we show that any two balanced combinatorial manifolds with boundary which are PL-homeomorphic can be transformed one into the other by a sequence of shellings and inverse shellings which preserve both the coloring and the topological type at each step. This solves a problem proposed by Izmestiev, Klee and Novik. Chapter 5 is devoted to the study of certain algebraic invariants of simplicial complexes in the balanced case. Here upper bounds for the graded Betti numbers of the Stanley-Reisner ring of balanced simplicial complexes are investigated in several level of generalities, and we show that they are sharper than in the general case. First, we employ Hochster formula to obtain inequalities for the case of arbitrary balanced complexes. Next, we focus on the balanced Cohen-Macaulay case and we obtain two upper bounds via two different strategies. Using similar ideas we also bound the Betti numbers in the linear strand of balanced normal d-pseudomanifolds, for d>2. Finally, we explicitly compute graded Betti numbers of the class of stacked cross-polytopal spheres, and conjecture that they provide a sharp upper bound for those of all balanced pseudomanifolds with the same dimension and number of vertices. In the last chapter, we implement cross-flips on balanced surfaces and 3-manifolds, and use this computer program to search for balanced manifolds on few vertices, possibly vertex-minimal. Reducing the barycentric subdivision of vertex minimal triangulations, we find a long list of balanced triangulations of interesting spaces on few vertices. Among those stand out a balanced vertex-minimal triangulation of the dunce hat (11-vertices) and of the 2- and 3-dimensional real projective space (9 and 16 vertices respectively). Using obstructions from knot theory and a careful choice of flips we find a balanced non-shellable 3-sphere and a balanced shellable non-vertex-decomposable 3-sphere on 28 and 22 vertices respectively. These are the smallest instances known in the literature.
Livres sur le sujet "Graded manifold"
1
Choquet-Bruhat, Yvonne. Graded bundles and supermanifolds. Napoli : Bibliopolis, 1989.
Trouver le texte intégral
2
Gurley, Ken. Manifold grace revealed in blood, water, and spirit. Hazelwood, MO : Word Aflame Press, 1993.
Trouver le texte intégral
3
Ibragimov, Zair. Topics in several complex variables : First USA-Uzbekistan Conference on Analysis and Mathematical Physics, May 20-23, 2014, California State University, Fullerton, California. Providence, Rhode Island : American Mathematical Society, 2016.
Trouver le texte intégral
4
Marques, Marcia Alessandra Arantes, dir. Pesquisa em Engenharia : Ciência e Aplicação. Bookerfield Editora, 2022. http://dx.doi.org/10.53268/bkf22040200.
Texte intégralRésumé :
Neste livro são apresentados resultados de trabalhos científicos aplicados à grande área de Engenharia. De abordagem objetiva, a obra se mostra de grande relevância para graduandos, alunos de pós-graduação, docentes e profissionais. Os capítulos estão agrupados em duas seções: i) materiais; ii) águas continentais e oceânicas. Pelo capítulo um é apresentado o desenvolvimento de uma metodologia para obter-se reprodutibilidade da área superficial de um eletrodo de estanho durante o estudo do crescimento de óxidos de estanho. A reprodutibilidade da área superficial pode ser comprovada pela reprodutibilidade das densidades de carga anódicas dos voltamogramas anódicos a 50 mVs-1 posteriores a cada tratamento. Por meio do capítulo dois é analisada a substituição de parte do carvão mineral, utilizado em siderúrgicas, por biomassa. Entre os grandes desafios do setor estão a produção de aço a preços competitivos e a substituição de parte do carvão mineral utilizado por biomassa. A biomassa é considera neutra em emissões de CO2, devido a captura do mesmo durante o processo de fotossíntese, o que a torna atraente para seu uso nos processos siderúrgicos. Além disso, o seu uso pode gerar redução de custos, principalmente se for considerado os rejeitos do agronegócio que não possuem um alto valor agregado. Neste contexto, por este capítulo serão mostradas algumas possíveis utilizações de biomassa nos processos siderúrgicos através de estudos que vem sendo realizado no tema e aplicações na indústria. Será possível notar que o uso de biomassa é uma alternativa viável a curto prazo para atender as crescentes restrições ambientais atuais. Através do capítulo três é analisado o crescimento voltamétrico de óxido de estanho em solução tampão fosfato, pH 8,7. Medidas elipsométricas ex-situ foram realizadas para determinar a espessura dos óxidos crescidos. A partir desses resultados, o volume do filme por unidade de carga, Vf, foi calculado para diferentes densidades de carga. As medidas elipsométricas mostram que filmes de óxido de estanho crescidos a 2 mVs-1 são menos densos para valores de espessura 3,37 nm, tendo Vf próximo a 1,70 x 10-4 cm3C-1. Para valores mais altos de espessura (11,0 – 12,4 nm) os filmes se tornam mais densos tendo Vf próximo a 0,5 x 10-4 cm3C-1. No caso de 100 mVs-1 os filmes apresentam o mesmo comportamento, tendo Vf próximo de 3,74 x 10-4 cm3.C-1 para espessura de 4,56 nm e Vf próximo de 1,32 x 10-4 cm3.C-1 para espessura de 7,42 nm. Imagens de Microscopia de Força Atômica mostraram que a morfologia muda e a rugosidade dos filmes aumenta com o aumento da espessura e do potencial final da voltametria. O capítulo quatro trata do Nitreto cúbico de boro (cBN), material imprescindível para usinagem com alta precisão e alta velocidade de APRESENTAÇÃO materiais ferrosos como aço. O cBN é recomendado para trabalhos sob condições severas, tais como corte intermitente, em que dureza deve estar associada com tenacidade para evitar a quebra. Na síntese do cBN, são aplicados, basicamente, dois tipos de catalisadores: nitreto de magnésio e magnésio. Cada qual oferece diferentes possibilidades, tais como maiores valores de profundidade de corte ou menor nível de rugosidade superficial. Este capítulo contribui para uma melhor compreensão da manipulação dos parâmetros aplicados no regime de síntese deste elemento e, favorecendo o desenvolvimento da tecnologia de sua produção. Por meio do capítulo cinco é avaliada a aplicação de separação magnética de alta intensidade no beneficiamento de itabiritos pobres. Na rota de processo avaliada (separação magnética + flotação), a etapa de separação magnética executa a função de pré-concentração e deslamagem. O teor de SiO2 no concentrado foi de 1,46% (menor que o teor objetivo de 2,00%). As recuperações mássica e metalúrgica obtidas com a rota separação magnética + flotação foram maiores em termos absolutos 3,3% e 4,4%, respectivamente. Através do capítulo seis é realizada a otimização de injeção de poliamida PA66 com 50% GF usando o método Taguchi. O estudo se justifica pela necessidade crescente de materiais mais leves e de maior produtividade em substituição às ligas metálicas, o que demanda o constante desenvolvimento de compósitos poliméricos e eficazes processos de fabricação. Como resposta do estudo, mediu-se a resistência máxima de tração (RTmáx), numa poliamida 66 com carga de 50% de fibra de vidro, Grivory GV-5H®. Fez-se uso da metodologia ANOVA para indentificar-se os fatores de maior significância para o processo. A melhor resistência máxima de tração obtida de 242,6 N/m2, mostrou-se como uma opção na substituição à aplicações de ligas metálicas de alumínio. A melhor resultado se obteve com a temperatura de processamento em 270°C, o fluxo volumétrico de 83 cm³/s, a pressão de recalque de 300 bar, a contrapressão de 10 bar, velocidade da rosca de 50 min-1 e o tempo de recalque com valor de 5 s. As porcentagens de contribuição encontradas foram pressão de recalque com contribuição de 61%, seguido da temperatura de processamento, com contribuição de 17% e em terceiro, o fluxo volumétrico com contribuição de 12%. A instalação de grandes equipamentos submarinos em águas profundas apresenta uma série de desafios. O capítulo sete trata da análise de estabilidade hidrodinâmica de Manifolds submarinos durante a instalação pelo método pendular. O presente capítulo racionaliza tal método e, além disso, considera sistemas para evitar o capotamento, durante um momento crítico do método que é o início da descida, apresentando uma modelagem matemática fenomenológica a partir de casos similares. A etapa de validação foi realizada pela análise comparativa entre a modelagem proposta e resultados de testes experimentais realizados com modelos físicos. Com a confirmação da aderência dos resultados numéricos com os experimentos, esta abordagem se confirma como uma ferramenta de engenharia para dimensionamento dos equipamentos submarinos instalados pelo Método Pendular para que sejam direcionalmente estáveis. Por meio do capítulo oito são apresentados os resultados da simulação da distribuição espacial das ondas geradas pela ação de ventos severos sobre o reservatório da barragem de Salto Caxias, no rio Iguaçu, estado do Paraná. Os ventos severos foram estimados através da análise de frequência regional para várias estações anemométricas do Instituto Meteorológico do Paraná (SIMEPAR) para o período de 1998 a 2005. As alturas de ondas foram estimadas pelo método paramétrico SMB, que usa como dados de entrada o fetch e a velocidade do vento. O método SMB foi aplicado pelo modelo computacional ONDACAD. Os testes estatísticos indicaram que a distribuição de Wakeby foi a mais robusta para as séries curtas de ventos horários máximos anuais, produzindo estimativas de ventos severos que variaram entre 25,7 ms-1 (tempo de retorno de Tr=10 anos) a 50,9 ms-1 (Tr=100 anos). O estudo presta grande contribuição à compreensão da quantificação das alturas de ondas geradas por ventos severos neste importante reservatório do estado do Paraná. Pelo capítulo nove é apresentada uma análise comparativa bidimensional entre alturas de ondas resultantes da aplicação dos modelos paramétricos MARQUES e JONSWAP ao reservatório da Usina Hidrelétrica de Itaipu Binacional, localizado no Rio Paraná entre o Brasil e o Paraguai. Os campos de vento uniforme relacionados a períodos de recorrência de 10, 20, 50 e 100 anos foram obtidos pelos registros realizados pelo Sistema Meteorológico do Paraná (SIMEPAR). Através da utilização do modelo ONDACAD foram determinados os campos de fetch e a transformação em campos de ondas pela utilização dos modelos paramétricos MARQUES e JONSWAP. Ao proceder a análise constatou-se que, ao majorar os resultados do modelo JONSWAP em 78% chega-se aos resultados bidimensionais gerados pelo modelo Marques. Esta condição foi verificada para situações de ventos extremos, ou seja, superiores a 20ms-1 e corpos hídricos que possuem fetch máximo da ordem de 10 quilômetros. O estudo contribui para a compreensão da distribuição das magnitudes das alturas de ondas neste reservatório de grande importância no âmbito da América do Sul, de grande utilidade para estudos relacionados, por exemplo, a erosões marginais, ecossistemas aquáticos continentais, psicultura por tanques-rede, quantificação de gases de efeito estufa devido à ressuspensão de sedimentos devido a propagação de ondas.
5
Marques, Marcia Alessandra Arantes, dir. Pesquisa em Engenharia : Ciência e Aplicação. Bookerfield Editora, 2022. http://dx.doi.org/10.53268/bkf22040200.
Texte intégralRésumé :
Neste livro são apresentados resultados de trabalhos científicos aplicados à grande área de Engenharia. De abordagem objetiva, a obra se mostra de grande relevância para graduandos, alunos de pós-graduação, docentes e profissionais. Os capítulos estão agrupados em duas seções: i) materiais; ii) águas continentais e oceânicas. Pelo capítulo um é apresentado o desenvolvimento de uma metodologia para obter-se reprodutibilidade da área superficial de um eletrodo de estanho durante o estudo do crescimento de óxidos de estanho. A reprodutibilidade da área superficial pode ser comprovada pela reprodutibilidade das densidades de carga anódicas dos voltamogramas anódicos a 50 mVs-1 posteriores a cada tratamento. Por meio do capítulo dois é analisada a substituição de parte do carvão mineral, utilizado em siderúrgicas, por biomassa. Entre os grandes desafios do setor estão a produção de aço a preços competitivos e a substituição de parte do carvão mineral utilizado por biomassa. A biomassa é considera neutra em emissões de CO2, devido a captura do mesmo durante o processo de fotossíntese, o que a torna atraente para seu uso nos processos siderúrgicos. Além disso, o seu uso pode gerar redução de custos, principalmente se for considerado os rejeitos do agronegócio que não possuem um alto valor agregado. Neste contexto, por este capítulo serão mostradas algumas possíveis utilizações de biomassa nos processos siderúrgicos através de estudos que vem sendo realizado no tema e aplicações na indústria. Será possível notar que o uso de biomassa é uma alternativa viável a curto prazo para atender as crescentes restrições ambientais atuais. Através do capítulo três é analisado o crescimento voltamétrico de óxido de estanho em solução tampão fosfato, pH 8,7. Medidas elipsométricas ex-situ foram realizadas para determinar a espessura dos óxidos crescidos. A partir desses resultados, o volume do filme por unidade de carga, Vf, foi calculado para diferentes densidades de carga. As medidas elipsométricas mostram que filmes de óxido de estanho crescidos a 2 mVs-1 são menos densos para valores de espessura 3,37 nm, tendo Vf próximo a 1,70 x 10-4 cm3C-1. Para valores mais altos de espessura (11,0 – 12,4 nm) os filmes se tornam mais densos tendo Vf próximo a 0,5 x 10-4 cm3C-1. No caso de 100 mVs-1 os filmes apresentam o mesmo comportamento, tendo Vf próximo de 3,74 x 10-4 cm3.C-1 para espessura de 4,56 nm e Vf próximo de 1,32 x 10-4 cm3.C-1 para espessura de 7,42 nm. Imagens de Microscopia de Força Atômica mostraram que a morfologia muda e a rugosidade dos filmes aumenta com o aumento da espessura e do potencial final da voltametria. O capítulo quatro trata do Nitreto cúbico de boro (cBN), material imprescindível para usinagem com alta precisão e alta velocidade de APRESENTAÇÃO materiais ferrosos como aço. O cBN é recomendado para trabalhos sob condições severas, tais como corte intermitente, em que dureza deve estar associada com tenacidade para evitar a quebra. Na síntese do cBN, são aplicados, basicamente, dois tipos de catalisadores: nitreto de magnésio e magnésio. Cada qual oferece diferentes possibilidades, tais como maiores valores de profundidade de corte ou menor nível de rugosidade superficial. Este capítulo contribui para uma melhor compreensão da manipulação dos parâmetros aplicados no regime de síntese deste elemento e, favorecendo o desenvolvimento da tecnologia de sua produção. Por meio do capítulo cinco é avaliada a aplicação de separação magnética de alta intensidade no beneficiamento de itabiritos pobres. Na rota de processo avaliada (separação magnética + flotação), a etapa de separação magnética executa a função de pré-concentração e deslamagem. O teor de SiO2 no concentrado foi de 1,46% (menor que o teor objetivo de 2,00%). As recuperações mássica e metalúrgica obtidas com a rota separação magnética + flotação foram maiores em termos absolutos 3,3% e 4,4%, respectivamente. Através do capítulo seis é realizada a otimização de injeção de poliamida PA66 com 50% GF usando o método Taguchi. O estudo se justifica pela necessidade crescente de materiais mais leves e de maior produtividade em substituição às ligas metálicas, o que demanda o constante desenvolvimento de compósitos poliméricos e eficazes processos de fabricação. Como resposta do estudo, mediu-se a resistência máxima de tração (RTmáx), numa poliamida 66 com carga de 50% de fibra de vidro, Grivory GV-5H®. Fez-se uso da metodologia ANOVA para indentificar-se os fatores de maior significância para o processo. A melhor resistência máxima de tração obtida de 242,6 N/m2, mostrou-se como uma opção na substituição à aplicações de ligas metálicas de alumínio. A melhor resultado se obteve com a temperatura de processamento em 270°C, o fluxo volumétrico de 83 cm³/s, a pressão de recalque de 300 bar, a contrapressão de 10 bar, velocidade da rosca de 50 min-1 e o tempo de recalque com valor de 5 s. As porcentagens de contribuição encontradas foram pressão de recalque com contribuição de 61%, seguido da temperatura de processamento, com contribuição de 17% e em terceiro, o fluxo volumétrico com contribuição de 12%. A instalação de grandes equipamentos submarinos em águas profundas apresenta uma série de desafios. O capítulo sete trata da análise de estabilidade hidrodinâmica de Manifolds submarinos durante a instalação pelo método pendular. O presente capítulo racionaliza tal método e, além disso, considera sistemas para evitar o capotamento, durante um momento crítico do método que é o início da descida, apresentando uma modelagem matemática fenomenológica a partir de casos similares. A etapa de validação foi realizada pela análise comparativa entre a modelagem proposta e resultados de testes experimentais realizados com modelos físicos. Com a confirmação da aderência dos resultados numéricos com os experimentos, esta abordagem se confirma como uma ferramenta de engenharia para dimensionamento dos equipamentos submarinos instalados pelo Método Pendular para que sejam direcionalmente estáveis. Por meio do capítulo oito são apresentados os resultados da simulação da distribuição espacial das ondas geradas pela ação de ventos severos sobre o reservatório da barragem de Salto Caxias, no rio Iguaçu, estado do Paraná. Os ventos severos foram estimados através da análise de frequência regional para várias estações anemométricas do Instituto Meteorológico do Paraná (SIMEPAR) para o período de 1998 a 2005. As alturas de ondas foram estimadas pelo método paramétrico SMB, que usa como dados de entrada o fetch e a velocidade do vento. O método SMB foi aplicado pelo modelo computacional ONDACAD. Os testes estatísticos indicaram que a distribuição de Wakeby foi a mais robusta para as séries curtas de ventos horários máximos anuais, produzindo estimativas de ventos severos que variaram entre 25,7 ms-1 (tempo de retorno de Tr=10 anos) a 50,9 ms-1 (Tr=100 anos). O estudo presta grande contribuição à compreensão da quantificação das alturas de ondas geradas por ventos severos neste importante reservatório do estado do Paraná. Pelo capítulo nove é apresentada uma análise comparativa bidimensional entre alturas de ondas resultantes da aplicação dos modelos paramétricos MARQUES e JONSWAP ao reservatório da Usina Hidrelétrica de Itaipu Binacional, localizado no Rio Paraná entre o Brasil e o Paraguai. Os campos de vento uniforme relacionados a períodos de recorrência de 10, 20, 50 e 100 anos foram obtidos pelos registros realizados pelo Sistema Meteorológico do Paraná (SIMEPAR). Através da utilização do modelo ONDACAD foram determinados os campos de fetch e a transformação em campos de ondas pela utilização dos modelos paramétricos MARQUES e JONSWAP. Ao proceder a análise constatou-se que, ao majorar os resultados do modelo JONSWAP em 78% chega-se aos resultados bidimensionais gerados pelo modelo Marques. Esta condição foi verificada para situações de ventos extremos, ou seja, superiores a 20ms-1 e corpos hídricos que possuem fetch máximo da ordem de 10 quilômetros. O estudo contribui para a compreensão da distribuição das magnitudes das alturas de ondas neste reservatório de grande importância no âmbito da América do Sul, de grande utilidade para estudos relacionados, por exemplo, a erosões marginais, ecossistemas aquáticos continentais, psicultura por tanques-rede, quantificação de gases de efeito estufa devido à ressuspensão de sedimentos devido a propagação de ondas.
Chapitres de livres sur le sujet "Graded manifold"
1
Schimmrigk, Rolf, Steven Duplij, Antoine Van Proeyen, Władysław Marcinek, Gert Roepstorff, Władysław Marcinek, Władysław Marcinek et al. « Graded Manifold ». Dans Concise Encyclopedia of Supersymmetry, 173. Dordrecht : Springer Netherlands, 2004. http://dx.doi.org/10.1007/1-4020-4522-0_224.
Texte intégral
2
Kostant, B., et A. Novikoff. « Graded Manifolds, Graded Lie Theory, and Prequantization ». Dans Collected Papers, 650–779. New York, NY : Springer New York, 2022. http://dx.doi.org/10.1007/978-0-387-09585-1_21.
Texte intégral
3
Allendoerfer, C. B. « Differentiable Manifolds and Their Imbedding ». Dans Problemi di geometria differenziale in grande, 1–36. Berlin, Heidelberg : Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10895-2_1.
Texte intégral
4
Citti, Giovanna, Gianmarco Giovannardi, Manuel Ritoré et Alessandro Sarti. « Submanifolds of Fixed Degree in Graded Manifolds for Perceptual Completion ». Dans Lecture Notes in Computer Science, 47–55. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-80209-7_6.
Texte intégral
5
Deser, Andreas. « Star Products on Graded Manifolds and α’-corrections to Double Field Theory ». Dans Trends in Mathematics, 311–20. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-31756-4_24.
Texte intégral
6
O’ Mahony, Niall, Anshul Awasthi, Joseph Walsh et Daniel Riordan. « Latent Space Cartography for Geometrically Enriched Latent Spaces ». Dans Communications in Computer and Information Science, 488–501. Cham : Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-26438-2_38.
Texte intégralRésumé :
AbstractThere have been many developments in recent years on the exploitation of non-Euclidean geometry for the better representation of the relation between subgroups in datasets. Great progress has been made in this field of Disentangled Representation Learning, in leveraging information geometry divergence, manifold regularisation and geodesics to allow complex dynamics to be captured in the latent space of the representations produced. However, interpreting the high-dimensional latent spaces of the modern deep learning-based models involved is non-trivial. Therefore, in this paper, we investigate how techniques in Latent Space Cartography can be used to display abstract and representational 2D visualisations of manifolds.Additionally, we present a multi-task metric learning model to capture in its output representations as many metrics as is available in a multi-faceted fine-grained change detection dataset. We also implement an interactive visualisation tool that utilises cartographic techniques that allow dimensions and annotations of graphs to be representative of the underlying factors affecting individual scenarios the user can morph and transform to focus on an individual/sub-group to see how they are performing with respect to said metrics.
7
Tu, Loring W. « Differential Graded Algebras ». Dans Introductory Lectures on Equivariant Cohomology, 145–50. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691191751.003.0018.
Texte intégralRésumé :
This chapter investigates differential graded algebras. Throughout the chapter, G will be a Lie group with Lie algebra g. On a manifold M, the de Rham complex is a differential graded algebra, a graded algebra that is also a differential complex. If the Lie group G acts smoothly on M, then the de Rham complex Ω(M) is more than a differential graded algebra. It has in addition two actions of the Lie algebra: interior multiplication and the Lie derivative. A differential graded algebra Ω with an interior multiplication and a Lie derivative satisfying Cartan's homotopy formula is called a g-differential graded algebra. To construct an algebraic model for equivariant cohomology, the chapter first constructs an algebraic model for the total space EG of the universal G-bundle. It is a g-differential graded algebra called the Weil algebra.
8
Tu, Loring W. « Circle Actions ». Dans Introductory Lectures on Equivariant Cohomology, 161–66. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691191751.003.0020.
Texte intégralRésumé :
This chapter focuses on circle actions. Specifically, it specializes the Weil algebra and the Weil model to a circle action. In this case, all the formulas simplify. The chapter derives a simpler complex, called the Cartan model, which is isomorphic to the Weil model as differential graded algebras. It considers the theorem that for a circle action, there is a graded-algebra isomorphism. Under the isomorphism F, the Weil differential δ corresponds to a differential called the Cartan differential. An element of the Cartan model is called an equivariant differential form or equivariant form for a circle action on the manifold M.
9
Webb, Heather. « Viewing and Reading Gesture ». Dans Dante, Artist of Gesture, 1–13. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192866998.003.0001.
Texte intégralRésumé :
Abstract Dante’s Commedia is a poem that is densely packed with fine-grained descriptions of gesture and bodily movement; it is for this reason that the poem has lent itself so readily to countless remediations in paintings, drawings, films, and live performances. This introduction prepares the ground for addressing how those gestures render themselves visible, how they, in their particular instantiations, depend on known examples of vices and virtues, how gesture acts in Dante’s Commedia, and how readers can ‘view’ and respond to gesture in Dante. It is necessary to begin with a discussion of what is meant by gesture. Reason and intention distinguish human gestures. This is not to say, however, that Dante is uninterested in the act of reading bodies more broadly. While some gestures are language, working alongside words in the manifold processes of signifying, the Commedia also frequently dwells on legible but not intentionally expressive bodily signs.
10
Nicolaides, Demetris. « The Stepping-Stone to Truth ». Dans In Search of a Theory of Everything, 30–35. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190098353.003.0005.
Texte intégralRésumé :
In his search for the primary substance of matter, Anaximenes returned to the tangible world and chose air. And he explained the manifold of natural phenomena quantitatively, in terms of condensation and rarefaction of air (of one material of unchangeable nature). With these opposite processes in mind, it was no longer necessary to ascribe all sorts of different properties to each object—such as rigidity, softness, hotness, coldness—just how dense it was. This idea in itself has a certain truth. But from a grander point of view as regards the evolution of science, his theory was the stepping-stone to one of the most consequential truths of nature, the atom! Atomism, however, required first the development of all other great ideas conceived thereafter, including mathematics. The significance of mathematics as a practical method to describe nature had been realized first by the great Pythagoras because of his passion for numbers.
Actes de conférences sur le sujet "Graded manifold"
1
Wu, Qianying, Chi Zhang, Mehdi Asheghi et Kenneth Goodson. « Design and Fabrication of Graded Copper Inverse Opals (g-CIOs) for Capillary-Fed Boiling in High Heat Flux Cooling Applications ». Dans ASME 2020 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipack2020-2603.
Texte intégralRésumé :
Abstract Capillary-fed boiling in microporous copper inverse opals (CIOs) is capable of removing an excess of 1 kW/cm2 at 10–15 °C superheat over small wicking distances ∼ 200 μm. In order to remove heat from large area chips (> 1 cm2), longer capillary wicking distance is desired to reduce the manufacturing complexity of the 3D manifold for liquid delivery and vapor extraction. In this study, we propose graded copper inverse opals (g-CIOs) where smaller pores at the bottom provide high capillary pressure for liquid delivery, while larger pores at the top reduce viscous pressure drop for vapor extraction. This nonhomogeneous wicking material decouples the permeability and capillary pressure in the vertical and lateral directions, resulting in greater CHFs and capillary wicking distances. In this study, we demonstrate the feasibility of fabricating g-CIOs material with up to three different pore diameters (2 μm, 5 μm, and 10 μm) using a multi-step template sintering and copper electrodeposition process. We then leverage and expand upon a well-calibrated experimental model for the prediction of CHF in monoporous CIOs to map the performance metrics for g-CIOs. The model combines a hydraulic resistance network with Darcy’s law and accounts for the nonhomogeneous permeabilities in lateral and vertical directions. Using this model, we study the impact of total wick thickness and graded pore-size combinations on the critical heat fluxes and wicking distances. Our modeling results conclude that a two-layer g-CIOs can potentially reach ∼70% enhancement in the critical heat flux or ∼30% enhancement in the wicking length compared to monoporous CIOs of the same thickness. Our fabrication capability and preliminary modeling results offer the opportunity to design boiling tests with optimized g-CIOs and exploring the potential of dissipating high heat flux for large area cooling applications.
2
Nelson, Jeremy, Trace Silfies, Brian Crandall et Jorge Penso. « Review of Life Assessment and Repair Strategies for Hydrogen Reformer Furnace Outlet Header Castings ». Dans ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21555.
Texte intégralRésumé :
Abstract Steam methane reforming is the most common method of hydrogen production relevant for plants in the petroleum upgrading, downstream refining, methanol, and ammonia industries. Owner-operators of steam methane reformer furnaces continue to make repair and replacement decisions that involve the cast outlet manifold fittings. One key part of these plans is assessment of the weldability and remaining life of the cast components. The 20Cr-32Ni-1Nb alloy casting materials typically used in the outlet manifolds are usually operated in the low end of their creep temperature range but are subject to metallurgical aging mechanisms which reduce their ductility, weldability, homogeneity, and fracture toughness. This paper covers the practices employed by several owner-users to optimize the lifecycle costs of the outlet manifold castings. These practices include but are not limited to controlled materials specifications, in-situ weldability tests, non-destructive testing in-situ and destructive testing post service, and repair practices such as annealing heat treatments. This paper also includes a limited survey of several owner-users and their fleets of reformer heaters. The details in the survey include the population of affected cast manifold components, alloy grades for the castings and welds, operating temperature ranges, number of startup and shutdown cycles, ranges of time in service, generic design details, and repair case studies. Also discussed are recent improvements in the state of the art for high temperature materials property data-gathering, as well as the structural modeling via Finite Element Methods. These new technologies are opportunities for future work to develop better strategies in the areas of condition assessment, repair planning, and remaining life prediction, taking into account the relevant parameters of installed manifold components, including: specific aging behavior of the casting chemistry, component mechanical design details, as well as the welding and heat treatment parameters during initial fabrication and subsequent maintenance activities.
3
Santacreu, Pierre, Saghi Saedlou, Laurent FAIVRE, Antoine ACHER et Johan Leseux. « Ferritic Stainless Steel Grade with Improved Durability for High Temperature Exhaust Manifold ». Dans SAE 2011 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 2011. http://dx.doi.org/10.4271/2011-01-0194.
Texte intégral
4
Grisolia, Ottaviano, Lorenzo Scano, Francesco Piccini, Antonietta Lo Conte, Massimiliano De Agostinis et Stefano Fini. « Steam Generator Grade P91 Steel Components Creep-Assessment By Test After Extended Service ». Dans ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-60160.
Texte intégralRésumé :
Abstract Previous study carried out creep analysis for steam generator high-temperature-section two components, outflow tubing and manifold of the superheater harp: they may have been critical because of the long continued service (109,000 hours or twelve years) and loading conditions, including maximum operation temperature (565°C) and applied stress (65 MPa). Metallographic methods by replica had showed no evidence of the creep cavitation in all the positions considered for both tubing and manifold. In particular, they had not found any cavitation or phases affecting creep strength of the material in the base, HAZ and weld metal microstructure. Now, present study carries out investigation for the two components based on the next plant outage outcome, after further 20,000-hours service. Both metallographic methods and hardness measurements’ results would compare with previous ones providing microstructure evolution in the period.
5
Hjorth, Carl-Gustaf, et John C. Hebeisen. « Subsea Manifolds : An Alternate Fabrication Strategy Using HIP PM Near Net Shapes ». Dans ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71156.
Texte intégralRésumé :
The fabrication of near net shape powder metal (PM) components by hot isostatic pressing (HIP) has been an important manufacturing technology for steel and stainless steel alloys since about 1985. The manufacturing process involves inert gas atomization of powder, 3D CAD capsule design, sheet metal capsule fabrication and densification by HIP in very large pressure vessels. Since 1985, several thousand tonnes of parts have been produced. The major applications are found in the oil and gas industry especially in offshore applications, the industrial power generation industry, the pulp and paper industry and in pharmaceuticals and traditional engineering industries. Typically, the components replace castings, forgings and fabricated parts and are produced in grades such as martensitic steels, austenitic and duplex (ferritic/austenitic) stainless steels and nickel- based superalloys. The application of HIP PM near net shapes to manifolds for medium to high pressure use has a number of advantages compared to the traditional forging and welding approach. First, the need for machining of the components is reduced to a minimum and welding during final assembly is reduced substantially. Manifolds by HIP design reduce the necessary welding by 70–90%. Mechanical properties of the HIP PM part are isotropic and equal to the best forged properties in the flow direction as is demonstrated below. This derives from the fine uniform microstructure of the PM parts. The PM parts are significantly lighter in weight because of the need to stiffen the forged component at the location of the weldment for the intersecting passageway — the PM parts can be smoothly blended into the intersection without need for welding. Furthermore, the PM HIP components can be made with significantly reduced manufacturing lead-time, greater design flexibility and improved cost for the final component. The PM HIP near net shape route has received approval from both ASTM [1,2,3] and NACE [4] for specific steel, stainless steel and nickel base alloys. This paper reviews the manufacturing sequence for PM near net shapes and discusses the details of several successful applications. The application of the HIP PM process to subsea manifolds is highlighted.
6
White, Ramsey James, Fahd I. Alghunaimi et Norah W. Aljuryyed. « Field Water Management Using Inline Water Separation ». Dans ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211156-ms.
Texte intégralRésumé :
Abstract Increasing water-cuts is inevitable for mature oil fields in which water flooding is used to achieve higher recovery targets. As water rates increase, significant investments are required to debottleneck water handling facilities and pipelines. This paper summarizes a detailed assessment to find the benefits of implementing a separation process to improve water separation efficiency. Inline Water Separator is considered here to optimize capital expenditures, building on the experience of a field demonstration of the technology. A prototype pilot plant was installed demonstrating an Inline Water Separator technology. Using a set of different inlet conditions. The technology was able to achieve +70-80% separation efficiency and deoiled the water to a maximum oil-in-water concentration of 35 ppm reaching lower than the accepted oil in water discharge criteria for reinjection (Zhang et all). Building on the success of the prototype, a suggested roadmap was studied to expand the testing of the technology at further harsher conditions with heavier crude grades and test alternative Inline Water Separation Technologies. A business case assessment was also conducted to determine the feasibility of the Inline Water Separator solution versus conventional water handling upgrades. Alternative Inline Water Separator technologies were also looked at as modularly designed skids that are easily transportable. The skids can be installed at different locations such as remote well manifolds or immediately pre-inlet processing facility. A technical and economic assessment of Inline Water Separator was conducted. It was found to be an economically attractive alternative to implementing conventional extensive oil-water separation, crude oil desalting, water deoiling & injection and pipeline network upgrades. The benefit of IWS besides reduction in capital expenditures, enhanced oil-in-water and a reduced overall energy and chemical consumption also results in reduced operating expenditures. When IWS is installed at the well manifold the stud shows a that the water rate will be reduced in the trunkline downstream the inline water separator and therefore a reduce the backpressure on the well will accrue, which can potentially increase the oil rate. Another benefit that was found, this design will potentially enhance distribution of field water injection as separated water from the inline water separator can be rerouted to another desired location or flank. The study of the Inline Water Separator technology portfolio expansion is highly recommended as a strategy to optimize capital expenditures to manage increasing produced water rates. The paper provides the alternative solutions, potential benefits and business case assessment to justify potential deployment.
7
Ji, Wei, Xi Li, Yueting Zhuang, Omar El Farouk Bourahla, Yixin Ji, Shihao Li et Jiabao Cui. « Semantic Locality-Aware Deformable Network for Clothing Segmentation ». Dans Twenty-Seventh International Joint Conference on Artificial Intelligence {IJCAI-18}. California : International Joint Conferences on Artificial Intelligence Organization, 2018. http://dx.doi.org/10.24963/ijcai.2018/106.
Texte intégralRésumé :
Clothing segmentation is a challenging vision problem typically implemented within a fine-grained semantic segmentation framework. Different from conventional segmentation, clothing segmentation has some domain-specific properties such as texture richness, diverse appearance variations, non-rigid geometry deformations, and small sample learning. To deal with these points, we propose a semantic locality-aware segmentation model, which adaptively attaches an original clothing image with a semantically similar (e.g., appearance or pose) auxiliary exemplar by search. Through considering the interactions of the clothing image and its exemplar, more intrinsic knowledge about the locality manifold structures of clothing images is discovered to make the learning process of small sample problem more stable and tractable. Furthermore, we present a CNN model based on the deformable convolutions to extract the non-rigid geometry-aware features for clothing images. Experimental results demonstrate the effectiveness of the proposed model against the state-of-the-art approaches.
8
Grisolia, Ottaviano, et Lorenzo Scano. « Steam Generator Grade P91 Steel Components Creep-Assessment Through a Procedure for the Italian Code Application and Comparison With the ECCC Recommendations, American Standard ». Dans ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65108.
Texte intégralRésumé :
ASTM A 335-Grade P91 components of steam generators may be critical because of possible steel microstructure changes and/or embrittlement due to the FATT increase during service at high temperature: both phenomena may worsen the material creep behavior globally. Operation temperatures below 600°C such as in the worked case considered herein should be less critical; nevertheless, the worked case plan has included additional controls on microstructure also to have a reference for the future. Present study considers for the worked case steam generator the creep analysis of high-temperature-section (superheater / reheater) two components, outflow tubing and manifold: they may be critical because of the long continued service (110,000 hours or twelve years) and loading conditions (maximum operation temperature and applied stress at the intersection). Aim of the work is to compare life results from the Italian creep code with those predicted by the API 579-1; it also checks compatibility of results from the polynomial models in Italian, ECCC and API 579-1 procedures. Life results based on the Italian-code polynomial function are consistent with those based on the polynomial function proposed in ECCC: With preliminary stresses from pressure formulas, life estimates are a bit more conservative than the ECCC model’s. Finally, life results obtained through the API 579-1 Level 3 assessment appear consistent with those predicted by the Italian creep code, ECCC recommendations application.
9
Rao, Vencherla V. R. Seshagiri, Maddali V. S. Murali Krishna, T. Kishen Kumar Reddy, D. Srikanth et P. V. Krishna Murthy. « Experimental Investigations on DI Diesel Engine With Low Heat Rejection Combustion Chamber With Carbureted Ethanol and Crude Jatropha Oil ». Dans ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53259.
Texte intégralRésumé :
It has been found that the vegetable oils and alcohols (ethanol and methanol) are promising substitute fuels for diesel fuel, because they are renewable in nature. However drawbacks associated with crude vegetable oil (high viscosity and low volatility) and ethanol (low cetane number and low energy content) which cause combustion problems in CI engines, call for engine with hot combustion chamber. Investigations were carried out on single–cylinder, four–stroke, water cooled, 3.68 kW direct injection diesel engine at a speed of 1500 rpm to evaluate the performance of a engine with medium grade low heat rejection (LHR) combustion chamber. It consisted of an air gap insulated piston and an air gap insulated liner fuelled with crude jatropha oil and carbureted ethanol with varied injection timing and injector opening pressure. Carbureted ethanol was inducted into the engine through a variable jet carburetor. This carburetor was installed at the inlet manifold of the engine and ethanol was inducted at different percentages of crude vegetable oil at full load operation on mass basis. Aldehydes (measured by dinitrophenyl hydrazine method), particulate emissions and oxides of nitrogen were measured at full load operation of the engine. With maximum induction of ethanol, engine with LHR combustion chamber showed improved performance over conventional engine at 27°bTDC and optimized injection timing.
10
Ghiasian, Seyedeh Elaheh, Prakhar Jaiswal, Rahul Rai et Kemper Lewis. « From Conventional to Additive Manufacturing : Determining Component Fabrication Feasibility ». Dans ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-86238.
Texte intégralRésumé :
The use of additive manufacturing (AM) for fabricating industrial grade components has increased significantly in recent years. Numerous industrial entities are looking to leverage new AM techniques to enable fabrication of components that were typically manufactured previously using conventional manufacturing techniques such as subtractive manufacturing or casting. Therefore, it is becoming increasingly important to be able to rigorously evaluate the technical and economic feasibility of additively manufacturing a component relative to conventional alternatives. In order to support this evaluation, this paper presents a framework that investigates fabrication feasibility for AM from three perspectives: geometric evaluation, build orientation/support generation, and resources necessary (i.e., cost and time). The core functionality of the framework is enabled on voxelized model representation, discrete and binary formats of 3D continuous objects. AM fabrication feasibility analysis is applied to 34 various parts representing a wide range of manifolds and valves manufactured using conventional manufacturing techniques, components commonly found in the aerospace industry. Results obtained illustrate the capability and generalizability of the framework to analyze intricate geometries and provide a primary assessment for the feasibility of the AM process.