1,721,148 research outputs found
Description of magneto rheological behavior with internal variables
No full text[[abstract]]The macroscopic theory of magnetorheological (MR) fluids is investigated by the use of the tensorial and vectorial internal variables. After both variables are defined, the balance equations, entropy inequality and evolution equations can be obtained. Under the consideration of physical phenomena of MR fluids (the existence of yield stress and the elasticity of MR solids), some parameters in the evolution equations are suitably chosen. The discussion is focused on the expression of stress tensor and the mechanism of energy dissipation. Comparisons among the vectorial internal variable, the tensorial internal variable, and the Cauchy's deformation tensor are made to explicate the connection among the different approaches. Finally, taking account of the effect of the gradient of the vectorial internal variable, modified expressions for entropy inequality and rotational invariant are also discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.[[note]]SC
Extended irreversible thermodynamics approach to magnetorheological fluids
No full text[[abstract]]Magnetorheological (MR) fluids have the unique ability to change properties from those of a fluid to those of a solid in the presence of a magnetic field. In this paper, we present a phenomenological theory for MR fluids within the framework of extended irreversible thermodynamics (EIT), which relates the dynamics of the fluxes to the form of the nonequilibrium equation of state and introduces the elasticity of MR fluids in a natural way. The Gibbs equation and the entropy inequality are derived to present the energy transfer and dissipative mechanisms. In particular, the viscoelastic behavior of the pre-yield regime and the fluid behavior of the post-yield regime are discussed in depth. Finally, according to the entropy inequality, we propose a mechanical model of MR fluids that can characterize the duplicate phenomena of the fluid-solid transition. The results of a numerical analysis of this model correspond with those of the functional tests of an MR damper.[[note]]SC
A mixture model for magneto-rheological materials
No full text[[abstract]]To model the response of magnetorheological (MR) materials, a continuum theory for a mixture consisting of a fluid continuum and a solid one is developed. In this mixture theory, the structure composed of the magnetizable particles in MR fluids is treated as a solid continuum. The aim of this paper is two-fold. Firstly, we adopt the extended irreversible thermodynamics (EIT) approach as the thermodynamic framework to formulate the general dynamic equations of MR mixtures. Introducing the concept of plastic deformation of the solid continuum, the mechanisms of dissipation are discussed and the evolution equations for the fluxes are derived. Secondly, by virtue of this derivation we study the propagation of an acoustic wave through the MR fluids. This study shows that there exist two longitudinal acoustic waves propagating along the direction of an applied magnetic field.[[note]]SC
Wave equations of elastic type-II superconductors
No full text[[abstract]]It is shown that when the thermodynamic fluxes are included as independent thermodynamic state variables of the generalized entropy density, the constitutive equations for the conserved state variables and the evolution equations for the nonconserved state variables of elastic type-II superconductors can be derived systematically. In particular, the transport equations generalizing the Fourier law for heat transport and the time-dependent Ginzburg-Landau equation for the relaxation of superelectron are proposed in this paper.[[note]]SC
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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