1,720,991 research outputs found
Damage characterizations and simulation of selective laser melting fabricated 3D re-entrant lattices based on in-situ CT testing and geometric reconstruction
No full textIn recent years, metal additive manufacturing (AM) are widely employed for industrial applications, such as: biomedical, aerospace, automotive, marine and offshore sections. AM demonstrated superior manufacturing efficiencies and economic advantages for advanced lightweight industrial components with unlimited arbitrary topological layouts and complex internal microstructures, and are also employed for fabrication of auxetic materials and structures. In this paper, damage characterizations and mechanical behaviors of selective laser melting (SLM) fabricated 3D re-entrant lattices are investigated based on in-situ interrupted micro-CT test, and simulation based on geometric reconstructed models are performed for exploring the underlying failure mechanisms. Firstly, theoretical models for predicting the mechanical properties of 3D re-entrant lattice are developed, such as stiffness, Poisson's ratio and strength, etc. Secondly, the geometrical errors and fabrication defects of 3D reentrant lattices are analyzed based on 3D micro-CT scanning, in-situ micro-CT interrupted compression tests are performed for studying the deformation process and failure mechanisms. Finally, image finite element models with the detailed information of the shape, position and distribution of defects of the 3D reentrant lattices are constructed from 3D tomographic images, and numerical simulations are performed for studying the effects of the defects on the mechanical performances of the SLM additive manufactured 3D re-entrant lattice structures. It is shown that the failure behavior of the reentrant lattice is governed not only by its topology, but also by the geometric defects and surface defects. Moreover, the proposed interrupted in-situ micro-CT mechanical loading experiments and image finite element approaches can also shed lights on the relations between fracture failure around the edge and the powder adhesion. The damage evolution process is compared with the numerical simulation results to verify the materials failure modes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
PIV Study of behavior of interaction of twin fountains in homogenous fluid
No full textIn this study the behavior of the interaction of twin fountains in a homogeneous fluid is studied experimentally using flow visualization and noninvasive PIV technique over the range of 25⩽Re⩽400 and 1⩽Fr⩽5. The results show that the behavior can be categorized into several regimes: flapping steady; bobbing/flapping/steady; flapping unsteady;
bobbing/flapping unsteady; and unsteady circling, which are mapped onto a Re-Fr map
Variations on the Author
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Preliminary Study on Ductile Fracture of Imperfect Lattice Materials
No full textThe ductile fracture behavior of two-dimensional imperfect lattice material under dynamic stretching is studied by finite element analyses (FEA). Three isotopic lattice materials, including the regular hexagonal honeycomb, the Kagome lattice and the regular triangular lattice, are taken into account, which are made of an elastic/visco-plastic metal material. Two typical imperfections (vacancy defect and rigid inclusion) are introduced separately. The numerical results reveal novel deformation modes and crack growth patterns in the ductile fracture of lattice material. Various crack growth patterns as defined according to their profiles, such as "X"-type, "Butterfly"-type, "Petal"-type. Crack propagation could induce severe material softening and plastic dissipation of the lattices. Subsequently, the effects of the strain rate, relative density, microstructure topology, and defect type on the crack growth pattern, the associated macroscopic material softening and the knock-down of total plastic dissipation are investigated.Materials Science, MultidisciplinaryMaterials Science, Characterization & TestingEICPCI-S(ISTP)
Aspects on the use of wind lidar measurements up to 600 meters for wind energy stydies: wind profile, weibull distribution and boundary layer height
No full textWind turbine wakes; power deficit in clusters and wind farms
Full text linkThe purpose of this presentation is to present recent power deficit analysis based on wind farm measurements. The power deficit is used to validate wind farm prediction models for different inflow condition
Onset asymmetry and three-dimensionality in transitional round fountains in homogeneous fluid
No full textThe onset of entrainment and asymmetry, which occurs in transitional fountains with intermediate Fr and Re (1 150 and at a specific Re value with Fr > 0.5 are asymmetric and three-dimensional and the extents of their asymmetry and three-dimensionality strongly depends on Re and Fr respectively
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