1,720,970 research outputs found
A fluid–structure interaction framework for mechanical aortic valves: analyzing the effects of valve design and aortic curvature on hemodynamics
Get PDFAortic mechanical heart valves (MHVs) have been implanted for decades to treat aortic valve disease and remain a viable option when valve durability is prioritized. However, the non-physiological hemodynamics induced by MHVs may lead to adverse clinical outcomes. Fluid–structure interaction (FSI) simulations enable the analysis of the biomechanical interaction between MHVs and blood flow. This study presents a strongly coupled, boundary-fitted FSI framework for aortic MHVs, used to assess the impact of MHV design and aortic curvature on hemodynamics. Nine simulation scenarios were investigated, considering three commercially available MHVs and three idealized aortic geometries (one straight and two curved models). Overall, the framework proved to provide results for flow-rate waveforms, velocity fields, and leaflet kinematics aligning well with previous experimental and computational studies. The framework highlighted that: (i) MHV design influences velocity fields and large-scale vorticity transport in the aorta, with systolic differences among the three devices of up to 41% and 133% in average swirling strength and stretching, respectively; (ii) the straight aortic model underestimates systolic swirling strength (up to 56%) and stretching (up to 91%) compared to curved models. This FSI framework can support MHV development by analyzing different device designs and anatomical scenarios
The meshless finite element method
Get PDFA meshless method is presented which has the advantages of the good meshless methods concerning the ease of introduction of node connectivity in a bounded time of order n, and the condition that the shape functions depend only on the node positions. Furthermore, the method proposed also shares several of the advantages of the finite element method such as: (a) the simplicity of the shape functions in a large part of the domain; (b) C0 continuity between elements, which allows the treatment of material discontinuities, and (c) ease of introduction of the boundary conditions.Fil: Idelsohn, Sergio Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Oñate, Eugenio. Universidad Politecnica de Catalunya; EspañaFil: Calvo, Nestor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: del Pin, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin
Computational simulation of a double-deck bus dynamics in a bend turning coupled with crosswind effects
Get PDFStability of high-sided road vehicles (trucks, vans, double-deck buses, etc) is highly influenced by crosswinds. Double-deck buses have an increased demand in some countries of Latin America due to their large passenger transportation capability. The variable conditions of the roads and mass distribution of the bus, i.e. vehicle with all passengers in the lower/upper level, empty or full, coupled with the wind action acting on it may lead to dangerous situations. To further understand this subject, a computational fluid dynamics (CFD) simulation of a double-deck bus taking a bend road coupled with crosswind is performed in this work. Some comments about the open source CFD toolbox OpenFOAM implementation to reproduce some dynamics characteristics of the rollover instability are made.Fil: Castro, Hugo Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; ArgentinaFil: Adotti, Marcelo Italo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; ArgentinaFil: Medina, Julian. Universidad Nacional del Nordeste. Facultad de Ingeniería. Departamento de Estabilidad; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Paz, Rodrigo Rafael. Livermore Software Technology Corporation.; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: del Pin, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Caldichouri, Iñaki. Livermore Software Technology Corporation.; Estados UnidosXII Congreso Argentino de Mecánica ComputacionalSan Miguel de TucumánArgentinaAsociación Argentina de Mecánica Computaciona
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
A Lagrangian Approach Based on the Natural Neighbor Interpolation
Get PDFA Lagrangian formulation is constructed using the so-called Moving-Particle Semi-Implicit Method. The approximation scheme is then modified to incorporate the natural neighbor interpolation in the definition of the shape functions. In this way, a multi-scale method results. This method is presented as an alternative for solving partial-differential equations (PDE). Second-order convergence is achieved when uniform rectangular (finite-difference-type) grids are used. Laplace and Poisson equations are solved in somewhat more general geometries as examples; the method demonstrates the same second-order accuracy as classical finite-elements (FEM), but allows a different treatment of geometry potentially powerful for local mesh adaptation in particular
A Lagrangian Approach Based on the Natural Neighbor Interpolation
No full textA Lagrangian formulation is constructed using the so-called Moving-Particle Semi-Implicit Method. The approximation scheme is then modified to incorporate the natural neighbor interpolation in the definition of the shape functions. In this way, a multi-scale method results. This method is presented as an alternative for solving partial-differential equations (PDE). Second-order convergence is achieved when uniform rectangular (finite-difference-type) grids are used. Laplace and Poisson equations are solved in somewhat more general geometries as examples; the method demonstrates the same second-order accuracy as classical finite-elements (FEM), but allows a different treatment of geometry potentially powerful for local mesh adaptation in particular
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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