1,720,970 research outputs found
Two-scale homogenization for a model in strain gradient plasticity
No full textUsing the tool of two-scale convergence, we provide a rigorous mathematical setting for the homogenization result obtained by Fleck and Willis (J. Mech. Phys. Solids, 2004) concerning the effective plastic behaviour of a strain gradient composite material. Moreover, moving from deformation theory to flow theory, we prove a convergence result for the homogenization of quasistatic evolutions in the presence of isotropic linear hardening
QUASI-STATIC EVOLUTIONS IN LINEAR PERFECT PLASTICITY AS A VARIATIONAL LIMIT OF FINITE PLASTICITY: A ONE-DIMENSIONAL CASE
No full textIn the framework of the energetic approach to rate-independent evolutions, we show that one-dimensional linear perfect plasticity can be obtained by linearization as a variational limit of a finite plasticity model with hardening proposed by A. Mielke (SIAM J. Math. Anal., 2004)
A comparison between active strain and active stress in transversely isotropic hyperelastic materials
Full text linkActive materials are media for which deformations can occur in absence of
loads, given an external stimulus. Two approaches to the modeling of such
materials are mainly used in literature, both based on the introduction of a
new tensor: an additive stress in the active stress
case and a multiplicative strain in the active strain one. Aim
of this paper is the comparison between the two approaches on simple shears.
Considering an incompressible and transversely isotropic material, we design
constitutive relations for and so that
they produce the same results for a uniaxial deformation along the symmetry
axis. We then study the two approaches in the case of a simple shear
deformation. In a hyperelastic setting, we show that the two approaches produce
different stress components along a simple shear, unless some necessary
conditions on the strain energy density are fulfilled. However, such conditions
are very restrictive and rule out the usual elastic strain energy functionals.
Active stress and active strain therefore produce different results in shear,
even if they both fit uniaxial data. Our results show that experimental data on
the stress-stretch response on uniaxial deformations are not enough to
establish which activation approach can capture better the mechanics of active
materials. We conclude that other types of deformations, beyond the uniaxial
one, should be taken into consideration in the modeling of such materials
Infinitely many solutions for polyharmonic elliptic problems with broken symmetries
No full textBy means of a perturbation argument devised by P. Bolle, we prove the existence of infinitely many solutions
for perturbed symmetric polyharmonic problems with nonhomogeneous Dirichlet boundary conditions. An
extension to the higher order case of the estimate from below for the critical values due to K. Tanaka is obtained
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
