1,720,996 research outputs found
Nonlinear behaviour of a suspended cable under stationary and non-stationary loading
No full textIn cables, time-varying forces cause large amplitude oscillations involving mainly the low
modes. The contribution of higher modes may arise due to either internal coupling phenomena or peculiar
spatial distribution of the loading. Using analytical reduced models and finite element models, the paper
explores the relevance of the modal interactions in both planar and spatial response to harmonical in-
plane excitation and to out-of-plane wind turbulence with its spatial distribution
One to one resonant double hopf bifurcation in aeroelastic osciilators with tuned mass dampers
No full text
Non-linear dynamic response of suspended cables under turbulent wind excitation: analytical and numerical approaches
No full textThe dynamic behaviour of an elastic suspended cable under turbulent wind excitation is
investigated by means of both a numerical procedure and a semi-analytical method. The former is
based to the finite-element method, on complete non-linear modelling of drag forces and on step-
by-step implicit integration. The latter relies on the Galerkin method for the cable reduced order
discretization and on linearization of the drag forces; the first eight cable eigenfunctions are adopted
as shape functions. The discretized non-linear equations of motion are, then, numerically integrated.
Some of the hypotheses and criteria adopted in reduced order modelling are discussed and verified
through numerical analysis; the results of the two approaches are finally compared
Nonlinear interactions in cables investigated using analytical and finite element models
No full textIn cables, near resonance time-varying loading causes large amplitude oscillations involving mainly
the resonant mode. The contribution of higher modes may arise due to either internal coupling
phenomena or peculiar spatial distribution of the loading. Using analytical reduced models and
finite element models, the paper explores the relevance of the modal interactions in both planar
and spatial response to harmonical in-plane excitation and to out-of-plane wind turbulence with
its spatial distribution
Non linear response of a suspended cable under non stationary excitation
No full textThe richness of dynamic phenomena in suspended cables is well known. Using an analytical
and a finite element model the paper first explores, the relevance of the modal interactions in
the in-plane oscillations under harmonic excitation; secondly, the effects on the 3D spatial
response and, finally, the effects of the spatial distribution of the load for the multiharmonic
excitation case, representing wind turbulence. When reduced order analytical models are
used, the spatial distribution of turbulence is projected onto the cable modal base, thus
resulting in a reduced wind excitation. The effect of this reduction has been here studied both
for 1D and for a full 3D wind velocity field
Nonlinear oscillations of cables under harmonic loading using analytical and finite element models
No full textIn cables, near resonance time-varying loading causes large amplitude oscillations mainly involving the resonant mode. A relevant contribution of higher modes may arise as a result of nonlinear coupling phenomena. In this work, analytical and finite element models are used to study the modal interactions in both planar and spatial responses to harmonic in-plane and out-of-plane loads. The aim of the investigation is to compare the two approaches by examining the effectiveness of the analytical model in describing the response with few degrees of freedom and the ability of the nonlinear finite element procedure adopted to capture the complex features of cable dynamics, albeit limited to stable oscillation branches. To this aim a finite element procedure has been developed based on the formulation of a 3 node cable element, on a refined technique for controlling viscous damping and on a step-by-step algorithm for time integration. In parallel an analytical reduced model has been derived by discretizing the two integro-differential equations of motion in the two transverse displacement components of the cable; the eigenfunctions of the linearized equations of motion are used in expanding the solution. The analyses first explore a moderately taut cable and are then extended to the behavior of a slacker cable, in order to validate the simplifying kinematic assumptions introduced in the analytical models by comparing the obtained results with those furnished by the richer finite element models
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
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