1,720,963 research outputs found
Analyse numerique par elements finis d'ecoulements s'etablissant en domaines non bornes
No full textSIGLECNRS TD Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Transverse vibration analysis of Euler-Bernoulli beam carrying point masse submerged in fluid media
Get PDFInternational audienceIn the present paper, an analytical method is developed to investigate the effects of added mass on natural frequencies and mode shapes of Euler-Bernoulli beams carrying concentrated masse at arbitrary position submerged in a fluid media. A fixed-fixed beams carrying concentrated masse vibrating in a fluid is modeled using the Bernoulli-Euler equation for the beams and the acoustic equation for the fluid. The symbolic software Mathematica is used in order to find the coupled vibration frequencies of a beams with two portions. The frequency equation is deduced and analytically solved. The finite element method using Comsol Multiphysics software results are compared with present method for validation and an acceptable match between them were obtained. In the eigenanalysis, the frequency equation is generated by satisfying all boundary conditions. It is shown that the present formulation is an appropriate and new approach to tackle the problem with good accuracy
Theoretical and numerical investigations of frequency analysis of two circular cylinders oscillating in a incompressible viscous fluid
Get PDFA potential flow is presented in this paper for the analysis of the fluid-structure interaction systems including, but not limited to, the idealized human head. The model considers a cerebro-spinal fluid (CSF) medium interacting with two solid domain. The fluid field is governed by the linearized Navier–Stokes equation. A potential technique is used to obtain a general solution for a problem. The method consists in solving analytically partial differential equations obtained from the linearized Navier–Stokes equation. From the solution, modal shapes and stokes cells are shown. In the analysis, the elastic skull model and the rigid skull model are presented. A finite element analysis is also used to check the validity of the present method. The results from the proposed method are in good agreement with numerical solutions. The effects of the fluid thickness is also investigated
Three-dimensional investigation of the stokes eigenmodes in hollow circular cylinder
Get PDFhttp://dx.doi.org/10.1155/2013/857821This paper studies the influence of boundary conditions on a fluid medium of finite depth.We determine the frequencies and the modal shapes of the fluid.The fluid is assumed to be incompressible and viscous. A potential technique is used to obtain in three-dimensional cylindrical coordinates a general solution for a problem.The method consists in solving analytically partial differential equations obtained from the linearized Navier-Stokes equation. A finite element analysis is also used to check the validity of the present method. The results from the proposed method are in good agreement with numerical solutions. The effect of the fluid thickness on the Stokes eigenmodes is also investigated. It is found that frequencies are strongly influenced
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
Vibration Analysis of Euler-Bernoulli Beams Partially Immersed in a Viscous Fluid
Get PDFThe vibrational characteristics of a microbeam are well known to strongly depend on the fluid in which the beam is immersed. In this paper, we present a detailed theoretical study of the modal analysis of microbeams partially immersed in a viscous fluid. A fixed-free microbeamvibrating in a viscous fluid is modeled using the Euler-Bernoulli equation for the beams.The unsteady Stokes equations are solved using a Helmholtz decomposition technique in a two-dimensional plane containing the microbeams cross sections.The symbolic softwareMathematica is used in order to find the coupled vibration frequencies of beams with two portions. The frequency equation is deduced and analytically solved.The finite element method using ComsolMultiphysics software results is compared with present method for validation and an acceptable match between them was obtained. In the eigenanalysis, the frequency equation is generated by satisfying all boundary conditions. It is shown that the present formulation is an appropriate and new approach to tackle the problem with good accuracy
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
Modélisation de la palme de nage (influence de l'interaction fluide structure)
No full textReconnue comme une discipline sportive à part entière (CIO), la nage avec palmes est une activité en plein essor. La demande qualitative croissante du pratiquant a poussé les constructeurs à développer une grande variété de palmes. La présente thèse a pour sujet la modélisation de la palme de nage au travers d'une étude mécanique complète. En parcourant l'état de l'art du domaine, il est constaté que jusqu'ici, le travail des concepteurs a surtout été empirique. L'objectif de ce travail est d'obtenir des critères quantifiables relatifs aux propriétés mécaniques de la palme dans sa fonction de propulsion. Pour cela, une approche globale a été adoptée, visant à considérer à la fois les matériaux constitutifs de la palme, et son mode de fonctionnement dans un contexte d'interaction fluide-structure. Plusieurs approches de modélisation du problème sont développées, ainsi que des simulations numériques et des développements expérimentaux en milieu réel. Ce travail a permis l'obtention de résultats tant concernant l'outil palme que son comportement in situ. Finalement, cette étude permet de d'aborder des méthodologies ingénieur simples, directement applicables par les concepteurs et fabricants; et pourra servir de base évolutive aux travaux de recherche futurs.Recognized as a sport in its own (IOC), fin swimming is now a booming business. The increasing practitioners' demand regarding quality has pushed manufacturers to develop a wide range of edges. This thesis is about modeling the swim fin through a complete mechanical study. Considering the previous studies made in this field, it is apparent that the designers' work has been mainly empirical so far. The purpose of this study is to obtain quantifiable criteria related to the mechanical properties of the fin in its propulsion function. In order to do this, a global approach was adopted, by considering both the constituent materials of the fin, and the way it works in a fluid-structure interaction context. Several modeling approaches regarding this problem are developed, as well as numerical simulations and experimental developments in a real environment. This work showed results touching both the fin as tool and its performances in action. Finally, this study helps to define simple engineering methodologies, which can be directly used by designers and manufacturers, and it could serve future researches.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF
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