Letteratura scientifica selezionata sul tema "Curved meshes"
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Articoli di riviste sul tema "Curved meshes"
1
Rangarajan, Ramsharan, e Adrián J. Lew. "Universal meshes: A method for triangulating planar curved domains immersed in nonconforming meshes". International Journal for Numerical Methods in Engineering 98, n. 4 (4 marzo 2014): 236–64. http://dx.doi.org/10.1002/nme.4624.
Testo completo
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Kilian, Martin, Anthony S. Ramos Cisneros, Christian Müller e Helmut Pottmann. "Meshes with Spherical Faces". ACM Transactions on Graphics 42, n. 6 (5 dicembre 2023): 1–19. http://dx.doi.org/10.1145/3618345.
Testo completoAbstract (sommario):
Discrete surfaces with spherical faces are interesting from a simplified manufacturing viewpoint when compared to other double curved face shapes. Furthermore, by the nature of their definition they are also appealing from the theoretical side leading to a Möbius invariant discrete surface theory. We therefore systematically describe so called sphere meshes with spherical faces and circular arcs as edges where the Möbius transformation group acts on all of its elements. Driven by aspects important for manufacturing, we provide the means to cluster spherical panels by their radii. We investigate the generation of sphere meshes which allow for a geometric support structure and characterize all such meshes with triangular combinatorics in terms of non-Euclidean geometries. We generate sphere meshes with hexagonal combinatorics by intersecting tangential spheres of a reference surface and let them evolve - guided by the surface curvature - to visually convex hexagons, even in negatively curved areas. Furthermore, we extend meshes with circular faces of all combinatorics to sphere meshes by filling its circles with suitable spherical caps and provide a remeshing scheme to obtain quadrilateral sphere meshes with support structure from given sphere congruences. By broadening polyhedral meshes to sphere meshes we exploit the additional degrees of freedom to minimize intersection angles of neighboring spheres enabling the use of spherical panels that provide a softer perception of the overall surface.
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Zhang, Jiayi Eris, Jérémie Dumas, Yun (Raymond) Fei, Alec Jacobson, Doug L. James e Danny M. Kaufman. "Progressive Shell Qasistatics for Unstructured Meshes". ACM Transactions on Graphics 42, n. 6 (5 dicembre 2023): 1–17. http://dx.doi.org/10.1145/3618388.
Testo completoAbstract (sommario):
Thin shell structures exhibit complex behaviors critical for modeling and design across wide-ranging applications. Capturing their mechanical response requires finely detailed, high-resolution meshes. Corresponding simulations for predicting equilibria with these meshes are expensive, whereas coarse-mesh simulations can be fast but generate unacceptable artifacts and inaccuracies. The recently proposed progressive simulation framework [Zhang et al. 2022] offers a promising avenue to address these limitations with consistent and progressively improving simulation over a hierarchy of increasingly higher-resolution models. Unfortunately, it is currently severely limited in application to meshes and shapes generated via Loop subdivision. We propose Progressive Shells Quasistatics to extend progressive simulation to the high-fidelity modeling and design of all input shell (and plate) geometries with unstructured (as well as structured) triangle meshes. To do so, we construct a fine-to-coarse hierarchy with a novel nonlinear prolongation operator custom-suited for curved-surface simulation that is rest-shape preserving, supports complex curved boundaries, and enables the reconstruction of detailed geometries from coarse-level meshes. Then, to enable convergent, high-quality solutions with robust contact handling, we propose a new, safe, and efficient shape-preserving upsampling method that ensures non-intersection and strain limits during refinement. With these core contributions, Progressive Shell Quasistatics enables, for the first time, wide generality for progressive simulation, including support for arbitrary curved-shell geometries, progressive collision objects, curved boundaries, and unstructured triangle meshes - all while ensuring that preview and final solutions remain free of intersections. We demonstrate these features across a wide range of stress-tests where progressive simulation captures the wrinkling, folding, twisting, and buckling behaviors of frictionally contacting thin shells with orders-of-magnitude speed-up in examples over direct fine-resolution simulation.
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Khattri, Sanjay Kumar. "An Adaptive Quadrilateral Mesh in Curved Domains". Serdica Journal of Computing 3, n. 3 (3 novembre 2009): 249–68. http://dx.doi.org/10.55630/sjc.2009.3.249-268.
Testo completoAbstract (sommario):
An nonlinear elliptic system for generating adaptive quadrilateral meshes in curved domains is presented. The presented technique has been implemented in the C++ language with the help of the standard template library. The software package writes the converged meshes in the GMV and the Matlab formats. Grid generation is the first very important step for numerically solving partial differential equations. Thus, the presented C++ grid generator is extremely important to the computational science community.
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Zhang, Juan, Lin Hua e Fu Sheng Wang. "An Stress Correction Method Applied to Doubly Curved Composite Laminated Plate". Advanced Materials Research 148-149 (ottobre 2010): 523–28. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.523.
Testo completoAbstract (sommario):
Aim: presents a stress correction method to improve calculation accuracy of doubly curved composite laminated plate with big meshing size to save computational effort. With the application of Marc’s secondary development function, a subroutine is embedded to simulate the mechanical properties of material, and the amendment factors are added so that the stress calculation results have the same computational accuracy when the model is compartmentalized to big meshes as the case under small meshes. We Compare the calculation results in big meshes and what in small meshes, which prove the error request can be satisfied.
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Kozhemyachenko, A. A., e A. V. Favorskaya. "Grid Convergence Analysis of Grid-Characteristic Method on Chimera Meshes in Ultrasonic Nondestructive Testing of Railroad Rail". Журнал вычислительной математики и математической физики 63, n. 10 (1 ottobre 2023): 1687–705. http://dx.doi.org/10.31857/s0044466923100071.
Testo completoAbstract (sommario):
A three-dimensional direct problem of ultrasonic nondestructive testing of a railroad rail treated as a linear elastic medium is solved by applying a grid-characteristic method on curved structured Chimera and Cartesian background meshes. The algorithm involves mutual interpolation between Chimera and Cartesian meshes that takes into account the features of the transition from curved to Cartesian meshes in three-dimensional space. An analytical algorithm for generating Chimera meshes is proposed. The convergence of the developed numerical algorithms under mesh refinement in space is analyzed. A comparative analysis of the full-wave fields of the velocity modulus representing the propagation of a perturbation from its source is presented.
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Ren, Yingying, Uday Kusupati, Julian Panetta, Florin Isvoranu, Davide Pellis, Tian Chen e Mark Pauly. "Umbrella meshes". ACM Transactions on Graphics 41, n. 4 (luglio 2022): 1–15. http://dx.doi.org/10.1145/3528223.3530089.
Testo completoAbstract (sommario):
We present a computational inverse design framework for a new class of volumetric deployable structures that have compact rest states and deploy into bending-active 3D target surfaces. Umbrella meshes consist of elastic beams, rigid plates, and hinge joints that can be directly printed or assembled in a zero-energy fabrication state. During deployment, as the elastic beams of varying heights rotate from vertical to horizontal configurations, the entire structure transforms from a compact block into a target curved surface. Umbrella Meshes encode both intrinsic and extrinsic curvature of the target surface and in principle are free from the area expansion ratio bounds of past auxetic material systems. We build a reduced physics-based simulation framework to accurately and efficiently model the complex interaction between the elastically deforming components. To determine the mesh topology and optimal shape parameters for approximating a given target surface, we propose an inverse design optimization algorithm initialized with conformal flattening. Our algorithm minimizes the structure's strain energy in its deployed state and optimizes actuation forces so that the final deployed structure is in stable equilibrium close to the desired surface with few or no external constraints. We validate our approach by fabricating a series of physical models at various scales using different manufacturing techniques.
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Hewett, Dennis W. "The Embedded Curved Boundary Method for Orthogonal Simulation Meshes". Journal of Computational Physics 138, n. 2 (dicembre 1997): 585–616. http://dx.doi.org/10.1006/jcph.1997.5835.
Testo completo
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Yang Hao e C. J. Railton. "Analyzing electromagnetic structures with curved boundaries on Cartesian FDTD meshes". IEEE Transactions on Microwave Theory and Techniques 46, n. 1 (1998): 82–88. http://dx.doi.org/10.1109/22.654926.
Testo completo
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Tellier, Xavier, Cyril Douthe, Laurent Hauswirth e Olivier Baverel. "Caravel meshes: A new geometrical strategy to rationalize curved envelopes". Structures 28 (dicembre 2020): 1210–28. http://dx.doi.org/10.1016/j.istruc.2020.09.033.
Testo completoTesi sul tema "Curved meshes"
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Gargallo, Peiró Abel. "Validation and generation of curved meshes for high-order unstructured methods". Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/275977.
Testo completoAbstract (sommario):
In this thesis, a new framework to validate and generate curved high-order meshes for complex models is proposed. The main application of the proposed framework is to generate curved meshes that are suitable for finite element analysis with unstructured high-order methods. Note that the lack of a robust and automatic curved mesh generator is one of the main issues that has hampered the adoption of high-order methods in industry. Specifically, without curved high-order meshes composed by valid elements and that match the domain boundary, the convergence rates and accuracy of high-order methods cannot be realized. The main motivation of this work is to propose a framework to address this issue.
First, we propose a definition of distortion (quality) measure for curved meshes of any polynomial degree. The presented measures allow validating if a high-order mesh is suitable to perform finite element analysis with an unstructured high-order method. In particular, given a high-order element, the measures assign zero quality if the element is invalid, and one if the element corresponds to the selected ideal configuration (desired shape and nodal distribution). Moreover, we prove that if the quality of an element is not zero, the region where the determinant of the Jacobian is not positive has measure zero. We present several examples to illustrate that the proposed measures can be used to validate high-order isotropic and boundary layer meshes.
Second, we develop a smoothing and untangling procedure to improve the quality for curved high-order meshes. Specifically, we propose a global non-linear least squares minimization of the defined distortion measures. The distortion is regularized to allow untangling invalid meshes, and it ensures that if the initial configuration is valid, it never becomes invalid. Moreover, the optimization procedure preserves, whenever is possible, some geometrical features of the linear mesh such as the shape, stretching, straight-sided edges, and element size. We demonstrate through examples that the implementation of the optimization problem is robust and capable of handling situations in which the mesh before optimization contains a large number of invalid elements. We consider cases with polynomial approximations up to degree ten, large deformations of the curved boundaries, concave boundaries, and highly stretched boundary layer elements.
Third, we extend the definition of distortion and quality measures to curved high-order meshes with the nodes on parameterized surfaces. Using this definition, we also propose a smoothing and untangling procedure for meshes on CAD surfaces. This procedure is posed in terms of the parametric coordinates of the mesh nodes to enforce that the nodes are on the CAD geometry. In addition, we prove that the procedure is independent of the surface parameterization. Thus, it can optimize meshes on CAD surfaces defined by low-quality parameterizations.
Finally, we propose a new mesh generation procedure by means of an a posteriori approach. The approach consists of modifying an initial linear mesh by first, introducing high-order nodes, second, displacing the boundary nodes to ensure that they are on the CAD surface, and third, smoothing and untangling the resulting mesh to produce a valid curved high-order mesh. To conclude, we include several examples to demonstrate that the generated meshes are suitable to perform finite element analysis with unstructured high-order methods.
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Pester, M. "Behandlung gekrümmter Oberflächen in einem 3D-FEM-Programm für Parallelrechner". Universitätsbibliothek Chemnitz, 1998. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199801386.
Testo completoAbstract (sommario):
The paper presents a method for generating curved
surfaces of 3D finite element meshes by mesh
refinement starting with a very coarse grid.
This is useful for parallel implementations where
the finest meshes should be computed and not read from
large files. The paper deals with simple geometries
as sphere, cylinder, cone. But the method may be
extended to more complicated geometries.
(with 45 figures)
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COSTA, JOAO MARCOS SILVA DA. "PROPERTIES OF DISCRETE SILHOUETTE CURVES ON PLANAR QUAD MESHES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36007@1.
Testo completoAbstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
No presente trabalho apresentamos um estudo de curvas silhuetas discretas sobre alguns tipos particulares de malhas, com o objetivo de avaliar propriedades dessas curvas. Nosso objeto de estudo são malhas quadrangulares, ou seja, onde todas as faces sejam quadriláteros e também sejam planares. Em particular dois tipos de malhas são discutidas: circular e cônica. Essas malhas são particularmente interessantes em arquitetura para modelagem de estrutura de vidros. A geração das malhas é feita aplicando-se um processo de otimização e em seguida, sobre essas malhas, definimos curvas discretas como candidatas a silhuetas e buscamos medidas de qualidade para essas curvas.
In this work we study discrete silhouette curves on Planar Quad meshes (PQ meshes), with the objective of evaluate some properties of these curves. PQ meshes correspond to planar quadrilaterals meshes, and our interest is focused particularly on two kinds of meshes: Conical and Circular. They are interesting in architecture for design with glass structures. An optimization process is applied for the mesh generation and we follow defining discrete curves on the meshes to obtain silhouette and to measure their quality.
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Wu, Sing-on, e 胡成安. "Smoothing the silhouettes of polyhedral meshes by boundary curve interpolation". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B2981554X.
Testo completo
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Wu, Sing-on. "Smoothing the silhouettes of polyhedral meshes by boundary curve interpolation /". Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21790942.
Testo completo
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USAI, FRANCESCO. "Structured meshes: composition and remeshing guided by the Curve-Skeleton". Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266879.
Testo completoAbstract (sommario):
Virtual sculpting is currently a broadly used modeling metaphor with rising
popularity especially in the entertainment industry. While this approach
unleashes the artists' inspiration and creativity and leads to wonderfully
detailed and artistic 3D models, it has the side effect, purely technical,
of producing highly irregular meshes that are not optimal for subsequent
processing. Converting an unstructured mesh into a more regular and struc-
tured model in an automatic way is a challenging task and still open prob-
lem.
Since structured meshes are useful in different applications, it is of in-
terest to be able to guarantee such property also in scenarios of part based
modeling, which aim to build digital objects by composition, instead of
modeling them from a scratch.
This thesis will present methods for obtaining structured meshes in two
different ways. First is presented a coarse quad layout computation method
which starts from a triangle mesh and the curve-skeleton of the shape. The
second approach allows to build complex shapes by procedural composition
of PAM's. Since both quad layouts and PAMs exploit their global struc-
ture, similarities between the two will be discussed, especially how their
structure has correspondences to the curve-skeleton describing the topology
of the shape being represented. Since both the presented methods rely on
the information provided by the skeleton, the difficulties of using automat-
ically extracted curve-skeletons without processing are discussed, and an
interactive tool for user-assisted processing is presented.
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Guo, Ruchi. "A Linear Immersed Finite Element Space Defined by Actual Interface Curve on Triangular Meshes". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79946.
Testo completoAbstract (sommario):
In this thesis, we develop the a new immersed finite element(IFE) space formed by piecewise linear polynomials defined on sub-elements cut by the actual interface curve for solving elliptic interface problems on interface independent meshes. A group of geometric identities and estimates on interface elements are derived. Based on these geometric identities and estimates, we establish a multi-point Taylor expansion of the true solutions and show the estimates for the second order terms in the expansion. Then, we construct the local IFE spaces by imposing the weak jump conditions and nodal value conditions on the piecewise polynomials. The unisolvence of the IFE shape functions is proven by the invertibility of the well-known Sherman-Morrison system. Furthermore we derive a group of fundamental identities about the IFE shape functions, which show that the two polynomial components in an IFE shape function are highly related. Finally we employ these fundamental identities and the multi-point Taylor expansion to derive the estimates for IFE interpolation errors in L2 and semi-H1 norms.Master of Science
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Machado, Luís Gustavo Pinheiro. "Malhas adaptativas em domínios definidos por fronteiras curvas". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-13012008-215606/.
Testo completoAbstract (sommario):
Dois métodos distintos são descritos e implementados. O primeiro método, proposto por Ruppert, possui garantias teóricas de qualidade quando a fronteira do domínio obedece certas restrições. O segundo método, proposto por Persson, possibilita um maior controle na densidade dos elementos que discretizam o domínio. As vantagens, desvantagens e particularidades de cada um dos métodos são descritas e detalhadasTwo distinct methods are described and implemented. The first method, proposed by Ruppert, has theoretical guarantees on the quality of elements when the domain boundaries respect certain restrictions. The second method, proposed by Persson, makes it possible to have greater control over the density of the elements that make up the domain. The advantages, disadvantages and specific points about each method are described and detailed
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Ghantous, Joyce. "Prise en compte de conditions aux bords d'ordre élevé et analyse numérique de problèmes de diffusion sur maillages courbes à l'aide d'éléments finis d'ordre élevé". Electronic Thesis or Diss., Pau, 2024. http://www.theses.fr/2024PAUU3024.
Testo completoAbstract (sommario):
Cette thèse porte sur l'analyse numérique d'équations aux dérivées partielles impliquant des conditions de bord d'ordre élevé de type Ventcel en utilisant la méthode des éléments finis. Afin de définir l'opérateur de Laplace-Beltrami intervenant dans la condition au bord, le domaine est supposé lisse : ainsi le domaine maillé ne correspond pas au domaine physique initial, entrainant une erreur géométrique. Nous utilisons alors des maillages courbes afin de réduire cette erreur et définissons un opérateur de lift permettant de comparer la solution exacte définie sur le domaine initial et la solution approchée définie sur le domaine discrétisé. Nous obtenons alors des estimations d'erreur a priori, exprimées en termes d'erreur d'approximation par éléments finis et d'erreur géométrique. Nous étudions des problèmes avec termes sources et des problèmes spectraux ainsi que des équations scalaires et les équations vectorielles de l'élasticité linéaire. Des expériences numériques en 2D et 3D valident et complètent ces résultats théoriques, soulignant en particulier l'optimalité des erreurs obtenues. Ces simulations permettent également d'identifier une super-convergence des erreurs sur les maillages quadratiquesThis thesis focuses on the numerical analysis of partial differential equations involving high-order boundary conditions of the Ventcel type using the finite element method. To define the Laplace-Beltrami operator involved in the boundary condition, the domain is assumed to be smooth: thus, the meshed domain does not correspond to the initial physical domain, resulting in a geometric error. We then use curved meshes to reduce this error and define a lift operator that allows comparing the exact solution defined on the initial domain with the approximate solution defined on the discretized domain. We obtain a priori error estimates, expressed in terms of finite element approximation error and geometric error. We study problems with source terms and spectral problems, as well as scalar equations and vector equations of linear elasticity. Numerical experiments in 2D and 3D validate and complement these theoretical results, particularly highlighting the optimality of the obtained errors. These simulations also identify a super-convergence of the errors on quadratic meshes
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Nascimento, Filipe de Carvalho. "Aproximação poligonal robusta de curvas implícitas". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-23112016-104719/.
Testo completoAbstract (sommario):
Modelagem geométrica envolvendo objetos implícitos é um tema de intensa pesquisa em Computação Gráfica. Portanto, obter técnicas eficientes para representar esses objetos é de extrema importância. Dois grupos de objetos implícitos relevantes para Computação Gráfica são as curvas implícitas e superfícies implícitas. As técnicas tradicionais para se aproximar curvas e superfícies implícitas envolvem dividir o domínio e buscar em suas partições partes da curva ou da superfície. Neste projeto propomos um novo métodos de poligonização robusta de curvas implícitas usando uma ferramenta numérica auto-validada chamada de Aritmética Afim. O método consiste na poligonização adaptativa de curvas implícitas em malhas triangulares tridimensionais.Geometric modeling involving implicit objects is a topic of intense research in Computer Graphics. Thus, obtain efficient techniques for representing these objects is of utmost importance. Two groups of relevant implicit objects for Computer Graphics are implicit curves and implicit surfaces. Traditional techniques for approximating implicit curves and surfaces involve splitting the domain and searching for parts of the curve or the surface. In this project we propose a new methods of robust polygonization of implicit curves using the self-validated numerical tool called Affine Arithmetic. The method consists in the adaptive polygonization of implicit curves in three-dimensional triangular meshes.
Libri sul tema "Curved meshes"
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Coelho, Maria Cristina Bueno, Juliana Barilli, Maurilio Antonio Varavallo, José Marcelo Imaña Encinas e Mauro Luiz Erpen. Viabilidade de Plantio da Espécie Calophyllum brasiliense. A cura di Marcia Alessandra Arantes Marques. Bookerfield Editora, 2021. http://dx.doi.org/10.53268/bkf21090700.
Testo completoAbstract (sommario):
A viabilidade técnica de plantios comerciais de Calophyllum brasiliense Cambess. foi avaliada na empresa JAMP Agropecuária e Reflorestadora Ltda. no município de Dueré, estado do Tocantins no período de 2009 a 2014 a partir da instalação de um inventário florestal sistemático contínuo. Foram amostrados 384 indivíduos em 35 ha distribuídos em 96 subparelas (0,96% de intensidade amostral) de 32m2 . O plantio apresentou baixa variabilidade (CV < 20%) para variável HT (CV = 14,82%) e para variável DAP (CV= 18,60%) aos 74 meses de idade. Também apresentou distribuição normal de frequência (≥ 68% dois indivíduos devem estar entre o intervalo de mais ou menos um desvio padrão da média) aos 74 meses tanto para a variável HT (68,70%) quanto para variável DAP (70,51%). A densidade do povoamento de 1.250 árvores/ha (espaçamento de 4 x 2m) mostrou que, aos 74 meses de idade, tem um crescimento da HT médio de 5,43 m (variando de 8,20 a 2,80m) com IMA de 0,88m e em DAP uma média de crescimento médio de 7,47 (variando de 12,96 a 3,5 cm) cm com IMA de 1,21 cm e com IMA em volume de 5,33 m3 /ha/ano. As curvas de produção para HT, DAP e volume feitas a partir do agrupamento dos IMA apresentou forma linear de crescimento indicando que o povoamento está em fase inicial de crescimento. A variação do crescimento da altura dominante pela idade foi determinada a partir da capacidade produtiva, onde foram construídas de cinco curvas de índice de sítio do tipo monomórficas, respectivamente de 1 a 9 m na idade índice de 74 meses (idade mais velha do povoamento) com intervalo de 2 m de forma a cobrir toda a amplitude de alturas totais observadas na área de estudo. Todos estes valores analisados em conjunto indicam que a espécie é viável para ser utilizada em plantios comerciais no estado do Tocantins.
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Pericão, Maria da Graça. Fundo Bibliográfico Antigo da Faculdade de Medicina da Universidade de Coimbra: séc. XV-XVIII. Imprensa da Universidade de Coimbra, 2020. http://dx.doi.org/10.14195/978-989-26-1827-2.
Testo completoAbstract (sommario):
Dos 581 títulos que constituem o fundo bibliográfico antigo da Faculdade de Medicina da Universidade de Coimbra e que abarcam os séculos XV a XVIII, cabem ao século XV apenas cinco, constituindo, assim, os denominados incunábulos, o núcleo mais antigo. Do século XVI podem destacar-se nomes como Amato Lusitano, Aristóteles, Avicena, Guido de Chauliac, Dioscórides, Hipócrates, Galeno, Jacopo da Forli, Rasis, o “damasceno” Mesue e Pedro Julião ou Pedro Hispano. Estes são os principais manuais que contêm, na sua maior parte, comentários aos clássicos gregos da medicina, particularmente Galeno, Hipócrates e Dioscórides, pois o estudo medieval feito a partir do comentário, geralmente traduzido graficamente pelo texto original da auctoritas a ocupar o centro da página, destacado pelo corpo do tipo e rodeado pelo comentário ou glosa, ainda estava muito presente no século XVI. Em matérias tão sensíveis como a Medicina, as afirmações tinham que estar fundamentadas em qualquer dos autores reconhecidos como autoridades. Do século XVII constam algumas obras de autores portugueses como Duarte Madeira Arrais, Manuel de Azevedo, Rodrigo de Castro (segundo alguns o fundador da obstetrícia portuguesa), Rodrigo da Fonseca, Tomás Rodrigues da Veiga e Abraão Zacuto, este impresso em Lyon e Amsterdão, tal como alguns dos atrás citados, o que atesta o reconhecimento internacional dos estudos destes autores portugueses. Do século XVIII, a par com as farmacopeias, avulta um número significativo de obras de cirurgia, algumas das quais de autoria portuguesa e numerosos dicionários de matéria médica, de História da Medicina e, curiosamente, dicionários portáteis de saúde, na linha dos tratados da saúde dos povos. Autores portugueses como Jacob de Castro Sarmento, João Curvo Semedo, Feliciano de Almeida e outros, publicam as suas obras em Portugal e no estrangeiro. Intensifica-se a produção de obras de Fisiologia, Física médica e medicina conservativa e preventiva. O presente trabalho descreve minuciosamente cada um dos exemplares deste fundo, dando especial relevo à sua proveniência atestada pelas numerosas notas manuscritas, na sua grande maioria congregações religiosas, de que se destaca a Livraria do Mosteiro de Santa Cruz dos Cónegos Regrantes de Santo Agostinho com 337 exemplares e alguns antigos colégios universitários que possuíam, de facto, em número e qualidade variados, núcleos bibliográficos que apoiavam as populações religiosas e estudantis que os frequentavam.
Capitoli di libri sul tema "Curved meshes"
1
Kainmueller, Dagmar. "ODDS for Segmentation of Highly Curved Structures". In Deformable Meshes for Medical Image Segmentation, 131–45. Wiesbaden: Springer Fachmedien Wiesbaden, 2014. http://dx.doi.org/10.1007/978-3-658-07015-1_9.
Testo completo
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Toulorge, Thomas, e Wim Desmet. "Spectral Properties of Discontinuous Galerkin Space Operators on Curved Meshes". In Lecture Notes in Computational Science and Engineering, 495–502. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-15337-2_48.
Testo completo
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Aparicio-Estrems, Guillermo, Abel Gargallo-Peiró e Xevi Roca. "Defining a Stretching and Alignment Aware Quality Measure for Linear and Curved 2D Meshes". In Lecture Notes in Computational Science and Engineering, 37–55. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-13992-6_3.
Testo completo
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Favorskaya, Alena V. "Simulation of the Human Head Ultrasound Study by Grid-Characteristic Method on Analytically Generated Curved Meshes". In Smart Modelling For Engineering Systems, 249–63. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-4709-0_21.
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Lu, Qiukai, e Mark S. Shephard. "Development of Unstructured Curved Meshes with G 1 Surface Continuity for High-Order Finite Element Simulations". In Lecture Notes in Computational Science and Engineering, 335–43. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19800-2_30.
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Ivrissimtzis, Ioannis. "Effects of Noise on Quantized Triangle Meshes". In Mathematical Methods for Curves and Surfaces, 274–84. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-11620-9_18.
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Bader, Michael. "Sierpinski Curves on Triangular and Tetrahedral Meshes". In Texts in Computational Science and Engineering, 181–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31046-1_12.
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Miura, Kenjiro Takai. "G2 Continuous Interpolation over Rational Curve Meshes". In Communicating with Virtual Worlds, 270–81. Tokyo: Springer Japan, 1993. http://dx.doi.org/10.1007/978-4-431-68456-5_22.
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Fortes, Miguel A., Pedro González, Maria Moncayo e Miguel Pasadas. "Multiresolution Analysis for Minimal Energy C r -Surfaces on Powell-Sabin Type Meshes". In Mathematical Methods for Curves and Surfaces, 209–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-11620-9_14.
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Min, Kyungha. "An A* Algorithm for Extracting Feature Curves from 3D Meshes". In Convergence and Hybrid Information Technology, 393–400. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32692-9_49.
Testo completoAtti di convegni sul tema "Curved meshes"
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Collins, Eric, e Edward Luke. "Evaluation of Curved Element Discontinuous Galerkin Meshes". In 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-5254.
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Kilian, Martin, Hui Wang, Eike Schling, Jonas Schikore e Helmut Pottmann. "Curved support structures and meshes with spherical vertex stars". In SIGGRAPH '18: Special Interest Group on Computer Graphics and Interactive Techniques Conference. New York, NY, USA: ACM, 2018. http://dx.doi.org/10.1145/3230744.3230787.
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Ruiz-Gironés, Eloi, e Xevi Roca. "Generation of Curved Meshes for the High-Lift Common Research Model". In AIAA AVIATION 2022 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2022. http://dx.doi.org/10.2514/6.2022-3807.
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Ferguson, Zachary, Pranav Jain, Denis Zorin, Teseo Schneider e Daniele Panozzo. "High-Order Incremental Potential Contact for Elastodynamic Simulation on Curved Meshes". In SIGGRAPH '23: Special Interest Group on Computer Graphics and Interactive Techniques Conference. New York, NY, USA: ACM, 2023. http://dx.doi.org/10.1145/3588432.3591488.
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Horeni, Bohumir, e Zdenek Chara. "Adaptive Meshing for Flow Calculation on Unstructured Meshes with Mixed Curved Elements". In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS: International Conference on Numerical Analysis and Applied Mathematics 2008. American Institute of Physics, 2008. http://dx.doi.org/10.1063/1.2991033.
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Galbraith, Marshall, Paul Orkwis e John Benek. "Discontinuous Galerkin Scheme Applied to Chimera Overset Viscous Meshes on Curved Geometries". In 42nd AIAA Fluid Dynamics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-3055.
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De Siqueira, Denise, Agnaldo Farias, Philippe Devloo e Sônia Gomes. "H (div) approximations based on hp-adaptive curved meshes using quarter point elements". In CNMAC 2016 - XXXVI Congresso Nacional de Matemática Aplicada e Computacional. SBMAC, 2017. http://dx.doi.org/10.5540/03.2017.005.01.0314.
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Lee, H., e M. Chen. "An Efficient Method for Flow Computations for Bodies With Curved Boundaries". In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33921.
Testo completoAbstract (sommario):
The difficulties of performing flow computations for bodies with arbitrary curved boundaries are well known. Many approaches have been advocated, but few have proven to be efficient, accurate, and simple to program. The earliest approach of using staircase boundaries to approximate curves is simple but crude, and would be prohibitively expensive if accurate, fine mesh results are desired. The use of meshes based on body-fitted curvilinear coordinates typically involve much more complex arithmetic and hence incur a high computational overhead. The inefficiency of curvilinear coordinates have spurred the current popularity of unstructured mesh formulations, which appear less restrictive but seem to lead to comparable overheads. The present paper describes a method based on returning to the intuitive concept of defining the boundary by placing boundary nodes on points of intersection of the boundary with the basic mesh lines. Such an arrangement creates locally acute non-uniform meshes which are well known to be ill-behaved. This is shown to be the consequence of singular behaviors in the limiting case of large “acuteness”, or the ratio of adjacent mesh increments. Differencing formulas and integration algorithms which are tolerant of such singularities, but retain the same order of accuracy as conventional nodes, are derived and used for all nodes adjacent to the boundary. In addition, algorithms for computing the normal and tangential gradients along the surface are also derived, based on vector combination of gradient components which can be easily evaluated from functions values at the nodes. Such gradients are needed for stress and pressure boundary conditions in flow computations. The method is demonstration by second order computations for the impersively started concentric cylinder Couette flow. It is shown that the method is efficient and produces accurate results.
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Galbraith, Marshall C., Paul D. Orkwis e John Benek. "Hole Cutting of Curved Discontinuous Galerkin Chimera Overset Meshes using a Direct Cut Method". In 21st AIAA Computational Fluid Dynamics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-2428.
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Wang, Ruiqin, e Xin Yan. "Background-Grid Based Mapping Approach to Film Cooling Meshing: Part I — Strategies and Test Cases". In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15768.
Testo completoAbstract (sommario):
Abstract Film cooling technique is commonly adopted in modern gas turbine engines to protect high-temperature components from erosion and damage caused by thermal stress. To improve film cooling effectiveness, many efficient prediction tools have been developed and have shown promising results, which are helpful for turbine aero-thermal design. For film cooling, evidence has shown that it is strongly affected by the momentum and heat transport in the boundary layer when hot gas and coolant are mixed downstream of the ejection. From the view of resolution accuracy in the boundary layer, structured grids will be the primary choice in fluid domain. However, the high-pressure gas turbine blades usually have several hundreds of cooling holes with different configurations and arrangements. Numerical simulations often face a big challenge in multi-block structured-grid generations when a large number of cooling holes are involved on curved hole-to-mainstream interfaces. Conventional block-splitting and mesh-generation for all holes are quite time-consuming and cumbersome, because the copying, translating and rotating manipulations cannot be applied on curved hole-to-mainstream interfaces directly. To solve these difficulties, this paper presents a novel mesh-generation strategy, which is a background-grid based mapping (BGBM) method, to generate multi-block structured grids for film-cooled blade efficiently without modifying the existing meshing tools and solvers, which is convenient for CFD users. It consists of three main steps: At first, the correspondence between physical space and computational space is established by two sets of background grids. Then, the sectional curves of geometry features in physical space are projected to the computational space. With these treatments, the curved hole-to-mainstream interfaces are flattened in computational space, where grids can be quickly generated with block copying, translating, rotating and merging manipulations. Thereafter, meshes in computational space are mapped back to the physical space based on the correspondence between physical and computational spaces, and high-quality structured-meshes can be obtained for numerical simulations. To demonstrate the presented meshing strategy, several typical cases with film cooling are selected for testing, including single cooling hole on curved surface, multiple rows of cooling holes on curved surface and NASA C3X vane with multiple hole arrays. In these cases, different holes, including the cylindrical holes and shaped holes with different ejection angles and arrangements, on curved interfaces are taken into consideration. The quality of generated structured grids for each test case is illustrated, which is able to meet the requirement of CFD solver. With the generated meshes, conjugate heat transfer performance in the turbine vane with different cooling arrangements is investigated and also validated with the existing experimental data.
Rapporti di organizzazioni sul tema "Curved meshes"
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Yao, J. Tracer Particle Locations with Curved or Arbitrary Planar Meshes. Office of Scientific and Technical Information (OSTI), maggio 2013. http://dx.doi.org/10.2172/1084709.
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Yan, Yujie, e Jerome F. Hajjar. Automated Damage Assessment and Structural Modeling of Bridges with Visual Sensing Technology. Northeastern University, maggio 2021. http://dx.doi.org/10.17760/d20410114.
Testo completoAbstract (sommario):
Recent advances in visual sensing technology have gained much attention in the field of bridge inspection and management. Coupled with advanced robotic systems, state-of-the-art visual sensors can be used to obtain accurate documentation of bridges without the need for any special equipment or traffic closure. The captured visual sensor data can be post-processed to gather meaningful information for the bridge structures and hence to support bridge inspection and management. However, state-of-the-practice data postprocessing approaches require substantial manual operations, which can be time-consuming and expensive. The main objective of this study is to develop methods and algorithms to automate the post-processing of the visual sensor data towards the extraction of three main categories of information: 1) object information such as object identity, shapes, and spatial relationships - a novel heuristic-based method is proposed to automate the detection and recognition of main structural elements of steel girder bridges in both terrestrial and unmanned aerial vehicle (UAV)-based laser scanning data. Domain knowledge on the geometric and topological constraints of the structural elements is modeled and utilized as heuristics to guide the search as well as to reject erroneous detection results. 2) structural damage information, such as damage locations and quantities - to support the assessment of damage associated with small deformations, an advanced crack assessment method is proposed to enable automated detection and quantification of concrete cracks in critical structural elements based on UAV-based visual sensor data. In terms of damage associated with large deformations, based on the surface normal-based method proposed in Guldur et al. (2014), a new algorithm is developed to enhance the robustness of damage assessment for structural elements with curved surfaces. 3) three-dimensional volumetric models - the object information extracted from the laser scanning data is exploited to create a complete geometric representation for each structural element. In addition, mesh generation algorithms are developed to automatically convert the geometric representations into conformal all-hexahedron finite element meshes, which can be finally assembled to create a finite element model of the entire bridge. To validate the effectiveness of the developed methods and algorithms, several field data collections have been conducted to collect both the visual sensor data and the physical measurements from experimental specimens and in-service bridges. The data were collected using both terrestrial laser scanners combined with images, and laser scanners and cameras mounted to unmanned aerial vehicles.
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Elizondo, Rocío. Los tres factores inteligibles de la curva de rendimiento en México. Banco de México, novembre 2023. http://dx.doi.org/10.36095/banxico/di.2023.13.
Testo completoAbstract (sommario):
En este documento se estiman para México los tres factores inteligibles de la curva de rendimientos considerados en Lengwiler y Lenz (2010), para el periodo 2001-2019. Estos factores se relacionan con las tasas de interés de distintos plazos y se identifican como el factor de largo, de corto y de curvatura. Los resultados más importantes destacan que, el factor de largo y de corto tienen su mayor peso en las tasas de más largo y corto plazos, respectivamente. Además, sus trayectorias están correlacionadas con la tasa a 10 años y la tasa de fondeo bancario, respectivamente. Por su parte, el factor de curvatura pesa más en las tasas de 3 meses a 2 años y su dinámica es similar a la expectativa de la tasa de corto plazo estimada para México. Así, este factor puede considerarse como un indicador de la expectativa de la política monetaria. Asimismo, los resultados encontrados para México son similares a los hechos estilizados que prevalecieron en las economías avanzadas de 1999 a 2010. Para una muestra extendida hasta 2021, los resultados se mantienen.
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Wijaya, Ignasius P. A., Eric Kreiger e Asuf Masud. An elastic-inelastic model and embedded bounce-back control for layered printing with cementitious materials. Engineer Research and Development Center (U.S.), gennaio 2024. http://dx.doi.org/10.21079/11681/48091.
Testo completoAbstract (sommario):
This paper presents a finite-deformation model for extrusion-based layered printing with cementitious materials. The evolution of mechanical properties as the printed material cures and stiffens results in nonphysical reduction in the magnitude of elastic strains when standard constitutive models are employed. This elastic recovery of the printing induced deformation contradicts the experimentally observed behavior of the printed cementitious materials that harden at a nearly-frozen deformed state. A thermodynamically motivated constraint on the evolution of elastic strains is imposed on the constitutive model to remedy the nonphysical bounce-back effect. An algorithm that is based on a strain-projection technique for the elastic part of deformation is developed that complements the inelastic response given by the Drucker–Prager model. It is then embedded in a finite strain finite element framework for the modeling and simulation of cure hardening and inelastic response of the early age cementitious materials. A ghost mesh method is proposed for continuous layer-wise printing of the material without the need for intermittent mesh generation technique or adaptive remeshing methods. The model is validated via comparison with experimental data and representative test cases are presented that investigate the mathematical and computational attributes of the proposed model.
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Figueiredo, Ana Beatriz, Arturo Daniel Alarcon Rodriguez, Bruno César Araújo, Clémentine Tribouillard, Dalve Alexandre Soria Alves, Dea Fioravante, Diego Arcia et al. Retomada nos municípios: Por onde começar. Inter-American Development Bank, aprile 2021. http://dx.doi.org/10.18235/0003234.
Testo completoAbstract (sommario):
Ao assumirem as prefeituras em 2021, os novos gestores e os gestores reeleitos se depararam com uma complexa realidade socioeconômica em virtude da pandemia, com desemprego e urgências sanitárias que vão emergindo a partir de uma segunda curva pandêmica. Podemos resumir que, neste quadro apreensivo, os desafios destes gestores, especialmente aqueles de cidades pequenas e médias são priorizar e optar por ações concretas que possam ser implementadas. Todas as necessidades são importantes, no há dúvidas. Entretanto, o estabelecimento de foco em alguns elementos da gestão pública pode resultar em uma abordagem mais pragmática para apoiar os municípios na retomada da economia e dos índices de qualidade de vida de seus cidadãos, tanto do ponto de vista imediato, quanto prospectando as condições necessárias para uma recuperação consistente nos próximos anos. Essa recuperação economica também deve ser sustentável, introduzindo medidas simples de mitigação e adaptação às mudanças climáticas. Assim, a retomada econômica trata da redução de despesas nos cofres públicos, possibilidades de crescimento econômico e geração de emprego e renda. Apresentamos nesta publicação sugestes de áreas a dedicar mais atenção nos próximos meses, tendo a inovação e o empreendedorismo como elementos transversais, reunindo produtos de conhecimento e material técnico do BID e de parceiros, iniciativas de organizações dedicadas a ajudar às cidades neste período único da história recente, e material multimídia de maneira sintética e esquemática, porém compreensiva aos problemas que mais afligem a população. E nas cidades onde tudo acontece, e no BID estamos comprometidos a atuar de maneira multissetorial, tendo os cidadãos como centro das intervenções e iniciativas que apoiamos. No cenário atual de apreensão em que nos encontramos, acreditamos que a priorização é uma maneira construtiva de criar as bases da sociedade que queremos quando as emergências se dissiparem. Esperamos que os gestores municipais encontrem neste material, de acordo com a sua realidade e necessidades locais, conteúdo útil para dirigirem esta jornada.
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Morales, Leonardo Fabio, Leonardo Bonilla, Luz Adriana Flórez, Catalina Granda, Didier Hermida, Francisco Lasso e Leonardo Fabio Morales. Continúa la pérdida de dinamismo en la ocupación y el comportamiento reciente del empleo en el sector de la construcción de edificaciones. Banco de la Republica, maggio 2024. http://dx.doi.org/10.32468/rml.30.
Testo completoAbstract (sommario):
En los últimos meses la ocupación continuó deteriorándose a un ritmo moderado. Según los datos de la Gran encuesta integrada de hogares (GEIH), la caída del empleo del agregado nacional fue del 1,8% en el último semestre, explicado principalmente por el área rural, mientras que el empleo urbano se mantiene estable. El débil desempeño del empleo también se observa en las tasas de ocupación (TO), que al mes de febrero presentaron caídas en todos los dominios. Por otro lado, el empleo asalariado, que durante la pospandemia impulsó la ocupación, en el periodo reciente permanece estable. Esta menor dinámica del empleo asalariado también se observa en registros administrativos de empleo asalariado y formal como la planilla integrada de liquidación de aportes (PILA) y las cajas de compensación familiar. Lo anterior explica los recientes incrementos en la tasa de informalidad, ubicándola en niveles del 55,8%. Finalmente, en el margen son cada vez más los sectores que contribuyen al decrecimiento del empleo, tales como transporte y comunicaciones; administración pública, salud y educación; construcción; comercio y alojamiento, y actividades profesionales. Acorde con el menor crecimiento en el empleo, los indicadores de vacantes y las expectativas de contratación por parte de las firmas continúan reduciéndose. Esta menor demanda explica el reciente repunte en la tasa de desempleo (TD), que para el mes de febrero de 2024 presentó un incremento en todos los dominios geográficos, ubicándola en niveles del 10,6% para el agregado nacional. A pesar de la menor demanda y el aumento en la TD, la curva de Beveridge muestra un mercado laboral aún apretado. En línea con lo anterior, se observan incrementos anuales en los ingresos laborales, tanto nominales como reales, estos últimos impulsados, en parte, por la corrección en la inflación de los últimos meses. Con base en la reciente dinámica del empleo y las proyecciones de crecimiento económico para 2024, los pronósticos para la TD mantienen una tendencia al alza. Así, se espera que la TD urbana se ubique en promedio entre el 9,6% y 11,9%, con un 10,8% como valor más probable. Para el agregado nacional se espera un comportamiento similar, con niveles promedio entre el 9,5% y 11,8%, con un 10,7% como valor más probable. Lo anterior sugiere una brecha de desempleo (diferencia entre la TD y la tasa de desempleo no inflacionaria, o Nairu) que se iría cerrando a lo largo del año, con -0,6 pp como valor promedio para 2024. Estas proyecciones sugieren una brecha de desempleo que se estaría moviendo hacia una zona neutral, y que se cerraría hacia finales de 2024. Como es usual, este reporte está divido en dos secciones. En la primera se describe la coyuntura actual del mercado laboral y en la segunda se realiza un análisis más detallado sobre el empleo en el sector de la construcción y su relación con la actividad económica. En Colombia, al igual que en las principales economías del mundo, la construcción es uno de los sectores más sensibles a los cambios en las condiciones financieras. Desde finales de 2022, sus principales indicadores han mostrado síntomas de desaceleración, lo cual se ha observado también en la creación de empleo, aunque con cierto rezago. En esta sección especial se evidencia que indicadores claves como el lanzamiento de viviendas nuevas, las unidades vendidas y la iniciación en la construcción de nuevas unidades lideran el comportamiento del empleo en el sector, resaltando la importancia de monitorear y analizar estos indicadores para prever posibles tendencias futuras.
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Bonilla, Leonardo, a cura di. Indicios de estabilización en el mercado laboral y una estimación de la tasa de desempleo desde el punto de vista de la firma. Banco de la República Colombia, novembre 2022. http://dx.doi.org/10.32468/rml.24.
Testo completoAbstract (sommario):
Con datos a agosto de 2022, todas las fuentes de información analizadas en este reporte, tanto las encuestas de hogares y como los registros de datos administrativos, muestran que el empleo mantiene crecimientos anuales importantes. La mayoría de indicadores del mercado laboral se encuentran en niveles similares o mejores a los presentados en el periodo prepandemia. Los segmentos que más aportaron al crecimiento en el empleo son el asalariado, el dominio de otras cabeceras y rural, y los segmentos poblacionales de mujeres, trabajadores sin educación superior y los no jefes de hogar. A pesar de las mejoras anuales destacables en los indicadores laborales, las series con ajuste estacional, que permiten la comparación mes tras mes de los indicadores, muestran que en los últimos meses el empleo, las vacantes y la participación laboral tienden a estabilizarse. Este comportamiento es más pronunciado en el mercado laboral urbano. Un indicador que muestra señales claras de estabilización es la tasa global de participación (TGP), que en el nivel nacional se ha mantenido alrededor del 63 % en el último semestre. La tasa de ocupación (TO) nacional también tiende a mantenerse estable desde julio, jalonada por el dominio urbano; mientras que en el dominio rural todavía se evidencian crecimientos mensuales de la ocupación. Este comportamiento explica la estabilización de la tasa de desempleo (TD) con ajuste estacional en el área urbana alrededor del 11,7 % y el mejor desempeño de la TD en el dominio rural y otras cabeceras, que en los últimos tres meses se redujo en casi 1 punto porcentual (pp). Por el lado de los salarios, se observan aumentos en los ingresos corrientes tanto en los segmentos asalariado como no asalariado. Sin embargo, la mayor inflación se traduce en que los salarios en el segmento asalariado hayan permanecido estables en términos reales. En el segmento no asalariado, caracterizado por su naturaleza más flexible, los ingresos laborales se han ajustado y se evidencian crecimientos reales anuales y trimestrales. Tanto los indicadores de holgura como los de cuellos de botella y las curvas de Beveridge muestran un mercado laboral estrecho. Dadas las previsiones en materia de crecimiento económico del equipo técnico del Banco de la República, consignadas en el Informe de Política Monetaria de octubre de 2022, los pronósticos indican que la TD urbana se mantendrá estable y terminaría 2022 alrededor del 11,2 % como escenario central. Para 2023 se prevé que dicho indicador, en promedio, se ubicaría entre el 9,9 % y 13,5 %, con un 11,7 % como valor más probable. Por el lado del dominio nacional, la tasa terminaría el año 2022 en el 10,6 %, y para 2023, en promedio, estaría entre el 9,2 % y 12,8 %, con un 11% como valor más probable. Estas predicciones implican ligeros incrementos en la TD durante 2023, los cuales serían consistentes con las menores previsiones de crecimiento económico para ese año. Por su parte, las estimaciones de la tasa de desempleo no inflacionaria (Nairu) sugieren una brecha de desempleo urbana negativa para finales de 2022. Estas estimaciones indicarían que la mayor estrechez del mercado laboral podría estar generando presiones inflacionarias; sin embargo, la brecha se vuelve no significativa en el año 2023. Este reporte se divide en dos secciones. La primera profundiza en los hechos coyunturales del mercado laboral descritos. La segunda estudia el tema de los indicadores de holgura del mercado laboral y la relación de estos con la inflación de salarios. Los indicadores de holgura son evaluados constantemente por los formuladores de política porque dan cuenta de la existencia de presiones inflacionarias desde el mercado laboral. La TD, que es el indicador de holgura laboral por excelencia, presenta algunas limitaciones que han sido suficientemente documentadas en la literatura especializada. Medidas análogas construidas a partir de información proveniente de las firmas, en ciertos contextos especiales, podrían tener mayor poder de predicción sobre la inflación de salarios. En este Reporte Especial se construye para Colombia la tasa de desempleo desde el punto de vista de la firma (TDF). La TDF es una modelación de la variación total de la TD que solo tiene en cuenta factores exclusivos de la demanda laboral de firmas, como son la tasa de vacantes (TV) y proxies de la tasa de renuncias. La TDF resultante supera a la TD en términos de predicción de inflación de salarios. Este nuevo indicador da luces sobre las señales mixtas que los indicadores de holgura mostraron al inicio de la pandemia, donde la TD presentó crecimientos exorbitantes, mucho mayores que las reducciones de la TV y, al mismo tiempo, los salarios nominales permanecieron constantes. Los resultados muestran que, en los primeros trimestres de la pandemia, la TD mostraba un mercado laboral bastante más holgado que la TDF. En la actualidad tanto la TD como la TDF están acopladas y muestran la misma señal en términos de la holgura del mercado laboral.
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Bonilla-Mejía, Leonardo, Luz Adriana Flórez, Didier Hermida-Giraldo, Francisco Javier Lasso-Valderrama, Leonardo Fabio Morales-Zurita, José David Pulido e Karen L. Pulido-Mahecha. Recuperación de la ocupación y dinámica reciente de la participación laboral. Banco de la República de Colombia, febbraio 2021. http://dx.doi.org/10.32468/rml.17.
Testo completoAbstract (sommario):
En la segunda mitad de 2020 el empleo continuó recuperándose, luego de su fuerte caída en el primer semestre. Sin embargo, en general, el mercado laboral todavía se encuentra bastante holgado como consecuencia de la crisis sanitaria por el covid-19, y muestra importantes disparidades entre grupos poblacionales y cambios en la composición de la ocupación. Respecto a las disparidades, las más notorias son las brechas de género, que se observan en ocupación, participación y desempleo. Por su parte, los cambios de composición del empleo son resultado de la recuperación más rápida de los segmentos no asalariado e informal vis a vis los segmentos asalariado y formal, algo previsible por su mayor flexibilidad y menores costos de entrada. Los ingresos laborales de los segmentos no asalariado e informal fueron los más afectados al inicio de la crisis y, aunque han registrado alguna recuperación, esta se debe fundamentalmente al aumento en sus horas trabajadas. La participación laboral también continúa recuperándose, pero los niveles siguen por debajo de los observados antes de la pandemia. Sin embargo, el crecimiento de la oferta laboral es menor que el de la ocupación, lo cual se ha visto reflejado en descensos consecutivos de la tasa de desempleo (TD). El ritmo de estos descensos, que fue importante al inicio de la recuperación del empleo, ha tendido a mermar en los últimos meses, dejando los registros de la TD en niveles aún considerablemente altos. Dadas estas altas TD y los bajos niveles que aún registran los índices de vacantes, la curva de Beveridge señala que el mercado laboral colombiano se encuentra significativamente holgado. Para 2021 se estima que la TD continuará decreciendo, aunque a un menor ritmo que el observado en la segunda mitad de 2020. Se espera que la TD nacional se ubique en promedio entre 12,5 % y 15,5 % en 2021, con 14 % como valor central. Las estimaciones de la TD de largo plazo consistente con una inflación estable (Nairu) sugieren una brecha de TD positiva de alrededor de 2,4 puntos porcentuales (pp) para 2021, por lo que la holgura del mercado laboral continuaría, aunque en menor grado que en 2020. Dado lo anterior, se esperaría que el mercado laboral no genere presiones al alza sobre la inflación durante 2021 por cuenta de costos salariales. Como es usual, este reporte se divide en dos secciones. En la primera se examinan en detalle los principales hechos coyunturales del mercado laboral. En la segunda se estudian los determinantes recientes de la participación laboral, y particularmente cómo la crisis sanitaria ha afectado la probabilidad de participación de distintos grupos poblacionales, de acuerdo tanto a sus características individuales como a las del hogar. Se encuentra que la pandemia provocó efectos negativos sobre la probabilidad de participar en mujeres, personas sin educación superior y pertenecientes a hogares con niños. En hogares con niños la pandemia aumenta la participación de hombres y reduce la de las mujeres, reflejando brechas importantes en la distribución de las actividades del cuidado. El efecto diferencial de la pandemia sobre las mujeres está concentrado en aquellas pertenecientes a hogares con niños, lo cual podría reflejar las limitaciones de los servicios de primera infancia y de los colegios durante la pandemia. A partir de este resultado se cuantifica la presión adicional sobre la oferta laboral y el desempleo que implicaría la total reapertura de estos servicios. Se estima que entre 159.000 y 205.000 mujeres regresarían a participar al mercado laboral, lo cual se traduciría en un aumento de la tasa global de participación entre 0,4 y 0,51 pp. En general, el efecto de este movimiento sobre el desempleo sería pequeño.
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/, Subgerencia de Política Monetaria e. Información Económica, Grupo de Análisis del Mercado Laboral (Gamla) /, Leonardo Bonilla, Luz Adriana Flórez, Didier Hermida-Giraldo, Francisco Javier Lasso-Valderrama, Leonardo Fabio Morales, Jose Pulido e Karen L. Pulido-Mahecha. Continúa la recuperación del mercado laboral y actualización de la Gran encuesta integrada de hogares. Banco de la República de Colombia, maggio 2022. http://dx.doi.org/10.32468/rml.22.
Testo completoAbstract (sommario):
A febrero de 2022 el mercado laboral mostró señales de recuperación, con un crecimiento sostenido en el empleo, observado tanto en las encuestas de hogares, como en los distintos registros administrativos. Las diferentes fuentes de información sugieren que el nivel de empleo se encuentra ligeramente por encima del registrado antes de la pandemia. El buen desempeño de la ocupación se observa en las ciudades y el área rural. Asimismo, la mayoría de los sectores económicos registraron aumentos en empleo. Los índices de vacantes, que reflejan la demanda de nuevos puestos de trabajo en el sector formal, reafirman el diagnóstico de un entorno favorable para el empleo. Los mayores crecimientos en las vacantes se presentan en ocupaciones de alto nivel de calificación, entre las cuales se destacan profesionales, científicos e intelectuales, y técnicos. Por el lado de la oferta laboral, también se observa una importante recuperación. Este comportamiento, junto con el mayor dinamismo en el empleo, se refleja en una reducción de la tasa de desempleo (TD) durante los últimos meses. Al desagregar las cifras de desempleo, se observa que la mayor reducción se ha registrado en el dominio urbano. Aunque todavía no se observan cambios importantes en los salarios, tanto los indicadores de holgura, como los de cuellos de botella y la curva de Beveridge muestran un mercado laboral que se va estrechando. Dadas las previsiones en materia de crecimiento económico del equipo técnico del Banco de la República para 2022, consignadas en el Informe de Política Monetaria de abril de 2022, los pronósticos ubican la TD nacional entre el 10 % y 11,9 % en promedio para dicho año. Por su parte, las estimaciones de la tasa de desempleo no inflacionaria (Nairu) sugieren una brecha de desempleo urbana cercanas a cero para 2022. Estas estimaciones indicarían que la menor holgura del mercado laboral ya no estaría generando presiones a la baja en la inflación. Este reporte se divide en dos secciones. En la primera se profundiza en los hechos coyunturales del mercado laboral anteriormente descritos. En la segunda se estudia la actualización de la Gran encuesta integrada de hogares (GEIH) realizada por el DANE, y los principales cambios que se generan en los indicadores del mercado laboral. Además de la actualización del marco geoestadístico y las proyecciones poblacionales construidas a partir del Censo nacional de población de 2018. La actualización de la encuesta sirvió para incorporar recomendaciones de organismos multilat erales, como la Organización Internacional del Trabajo (OIT) y la Organización para la Cooperación y el Desarrollo Económicos (OCDE), con el fin de mejorar la clasificación y caracterización de la población en edad de trabajar (PET), visibilizar estadísticamente a grupos poblacionales y llevar los indicadores del mercado laboral a nuevos estándares internacionales. Los principales cambios encontrados en los indicadores del mercado laboral obedecen a varios factores. En primer lugar, se actualizó el umbral de la PET, disminuyendo el nivel de la población fuera de la fuerza laboral (inactiva), al sustraer a cerca de 2,9 millones de menores entre 10 y 14 años. En segundo lugar, se modificó la forma de clasificar y caracterizar la población ocupada. No obstante, este cambio no parece tener impactos sustanciales en esta población. Así, lo más probable es que los cambios en el nivel de los ocupados que se observan obedezcan a la actualización del marco geoestadístico. Finalmente, la población desempleada es la que menos sufre cambios por la actualización de la encuesta. Adicionalmente, este reporte especial presenta una propuesta provisional de empalme y desestacionalización de los principales agregados del mercado laboral para el estudio de las dinámicas del mismo, que será empleada en este y en reportes futuros, hasta el momento en que el DANE publique series empalmadas y desestacionalizadas oficiales definitivas.
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LOCAL BUCKLING BEHAVIORS OF COLD-FORMED CIRCULAR HOLLOW SECTIONS HIGH STRENGTH STEEL STUB COLUMNS BASED ON A HIGH-FIDELITY NUMERICAL MODEL (ICASS’2022). The Hong Kong Institute of Steel Construction, agosto 2022. http://dx.doi.org/10.18057/icass2020.p.337.
Testo completoAbstract (sommario):
This paper establishes a high-fidelity numerical model to systematically investigate the local buckling behaviors of cold-formed circular hollow section (CHS) high-strength steel stub columns. Material nonlinearity and geometric nonlinearity are carefully accounted for in the FE model. Based on the Menegotto-Point model, the material constitutive of cold-formed CHS is calibrated considering the characteristics of the curvature of the stress-strain curve. The mesh is uniformly patterned according to the cross-section of the CHSs steel under compression. Subsequently, parametric studies are carried out to study the local buckling mode, buckling strength and ductility of the cold-formed high-strength CHS. The cross-sectional slenderness limit and local buckling strength of CHSs with material strength more than 500 MPa are proposed.