1,720,971 research outputs found
Comparaison des différentes théories de poutre non locale raffinée pour la flexion et l'analyse du flambement des nano-poutres
Get PDFIn this study, non unified local shear deformation theory is proposed to consider the bending and buckling of nano beams. This theory is based on the assumption that the cross-sectional and planar displacements consist of bending and shear components, shear components do not contribute to the bending moments. Motion equations are derived using the Hamilton’s principle. Analytical solutions for deformation, buckling load, and the natural frequency are presented to a nano simply supported beam, and the results obtained are compared to those proposed by the nonlocal Timoshenko beam theory and Reddy beam theoriesDans cette étude, la théorie de déformation de cisaillement non locale unifiée est proposée pour l’étude la flexion et le flambement des nano poutres. Cette théorie est basée sur l'hypothèse que les déplacements transversaux et plans sont constitués de composantes de flexion et de cisaillement, les composantes de cisaillement ne contribuent pas aux moments de flexion. Les équations du mouvement sont dérivées en utilisant le principe d’Hamilton. Des solutions analytiques pour la déformation, charge de flambement, et la fréquence naturelle sont présentées pour une nano-poutre simplement appuyée, et les résultats obtenus sont comparés à ceux proposés par la théorie des poutres non locales de Timoshenko et les théories des poutres de Reddy.Dans cette étude, la théorie de déformation de cisaillement non locale unifiée est proposée pour l’étude la flexion et le flambement des nano poutres. Cette théorie est basée sur l'hypothèse que les déplacements transversaux et plans sont constitués de composantes de flexion et de cisaillement, les composantes de cisaillement ne contribuent pas aux moments de flexion. Les équations du mouvement sont dérivées en utilisant le principe d’Hamilton. Des solutions analytiques pour la déformation, charge de flambement, et la fréquence naturelle sont présentées pour une nano-poutre simplement appuyée, et les résultats obtenus sont comparés à ceux proposés par la théorie des poutres non locales de Timoshenko et les théories des poutres de Reddy
Study of the Transverse Vibration for The Carbon Nanotubes
Get PDFThis study concerns the dynamic behavior of composite beams gradually evaluated through the thickness materials. Our work is devoted to the analysis of natural frequencies of composite beams FGM used in building structures in civil engineering often subjected to vibration loads due to earthquakes. The vibration characteristics of specific beams such as free and orthotropic fixed beams are studied without including deformation due to shear and rotational inertia. We introduce the effects of transverse deformation due to shear and rotational inertia for the accurate prediction of normal frequencies. An application to carbon nanotubes was investigated
Study of a Piezo-Thermo-Elastic Materials Console
Get PDFIn the first part of this work, analytical expressions were determined for the stresses through the thickness of a composite beam submitted to electrical excitation. In the second part of this study we are interested in the theory of elasticity, which is used to obtain exact solutions of piezo-thermo-elastic consoles gradually coupled evaluated under different loads. These solutions are used to identify the piezoelectric parameter and thermal coefficients of the materials. In addition, numerical results are obtained for the analysis of the loaded console by two different types of loading. In this study we show also that changing the linear thermal parameters of the material does not affect the distribution of the stress and the induction of the beam. However it affetcs the components of the deformation, electric field, the displacement and the electric potential of the console
Nonlinear Behavior of a Non-Homogeneous Plate in Cylindrical Bending under Uniform Loading
No full textIn this work, we will study the non-linear behavior of a plate in cylindrical bending using an exponential function with gradient of
material properties (Commonly called E-FG). The plates are subjected to uniform loading and geometric nonlinearity is introduced into relationship the stress-strain using the expressions nonlinear deformations of Von Karman's. The material properties of the plate, except the Poisson coefficient, are assumed to vary in the direction of thickness z in the form of an exponential law distribution. The solution is obtained by using the Prince of Hamilton. Numerical results by an exponential function with gradient of properties are given in the form of graphs non-dimensional; and determine the effect of the material properties on the deflection and the normal stress across the thickness
Comment on “Free transverse vibration of the fluid-conveying single-walled carbon nanotube using nonlocal elastic theory” [J. Appl. Phys. 103, 024302 (2008)]
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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
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