1,720,976 research outputs found
Efficient simulation of inclusions and reinforcement bars with the isogeometric Boundary Element method
No full textThe paper is concerned with the development of efficient and accurate solution procedures for the isogeometric boundary
element method (BEM) when applied to problems that contain inclusions that have elastic properties different to the computed
domain. This topic has been addressed in previous papers but the approach presented here is a considerable improvement in
terms of efficiency and accuracy.
One innovation is that initial stresses instead of body forces are used, resulting in discretised equations that can be written
using matrix–vector multiplications. This allowed a one step solution to be implemented for elastic inclusions. In addition, a
novel approach is used for the computation of strains, that avoids the use of highly singular fundamental solutions. Finally, a
new type of inclusion is presented that can be used to model reinforcement bars or rock bolts and where analytical integration
can be used. Test examples, where results are compared with Finite Element simulations, show that the proposed approach is
sound
Isogeometric Boundary Element Analysis of steady incompressible viscous flow, Part 1: Plane problems
No full textA novel approach is presented to the Boundary Element analysis of steady incompressible flow. NURBS basis functions are used for describing the geometry of the problem and for approximating the unknowns. In addition, the arising volume integrals are treated differently to published work, that is, volumes are described by bounding NURBS curves instead of cells and a mapping is used. The advantage of our approach is that non-trivial boundary shapes can be described with very few parameters and that no generation of cells is required. For the solution of the non-linear equations both classical and modified NewtonâRaphson methods are used. A comparison of the two methods is made on the classical example of a forced cavity flow, where accurate solutions are available in the literature. The results obtained agree well with published ones for moderate Reynolds numbers using both methods, but it is found that the latter requires a relaxation scheme and considerably more iterations to converge. Finally, it is shown on a practical example of an airfoil how more complex boundary shapes can be approximated with few parameters and a solution obtained with a small number of unknowns
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
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
Safety Assessment during Construction of Shotcrete Tunnel Shells Using Micromechanical Material Models
No full textA NURBS-BEM application in continuum damage mechanics
No full textIn this paper the integral equation approach is used to describe the propagation of continuum damage in three dimensional solids. The governing equation is of integral type and contains both boundary and domain integrals. Such integrals are computed with the aid of the NURBS functions. The subvolume involved by the damage is modelled by a special mapping procedure that avoids the use of the internal cells. The implementation is verified on a test case for which an analytical solution is available
A three-dimensional isogeometric boundary element analysis in elasto-plasticity
No full textOn the basis of some recent works of the authors, a three dimensional (3D) iso-geometric approach is here presented in the boundary-integral-equation-based 3D structural analysis. The domain under investigation presents plastic areas of predefined shape. The geometry of the plastic zone is modeled by the aid of two NURBS surfaces and of a special mapping method. The advantage over currently used methods is that no discretization into cells is required to evaluate the arising volume integrals. Moreover, the geometry independent approximation allows flexible refinement options. The boundary of the domain is also discretised by the use of multi-level NURBS discretization. The nonlinear system of equations is solved by a Newton Raphson scheme. One numerical example is provided with regard to a test case for which a comparison between modified and full Newton Raphson approach is performed
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