1,721,018 research outputs found
Pompey, Minerva and Rome’s presence in the near East
Full text linkThis paper deals with the political implications of the dedication of a temple to Minerva in Rome by Pompey the Great after his Eastern campaign (61 BC). Among the hypotheses on the reasons for the choice of this goddess by the general, Palmer’s – that this Minerva has to be put in connection with the Athena of Troy – is here considered as the most likely, and is thus analysed in depth. Pompey’s dedication arguably derives its meaning from earlier relationships between the Near East and Rome, and possibly more recent Mithridatic anti-Roman propaganda, and might symbolise the ecumenical character of Pompey’s conquests
A numerical comparison of Galerkin and Collocation Isogeometric approximations of acoustic wave problems
No full textIsogeometric collocation discretizations for acoustic wave problems
No full textThe acoustic wave problem is here discretized by collocation isogeometric analysis (IGA) in space and Newmark schemes of first and second order in time. A numerical study in the plane on both Cartesian and NURBS domains investigates the convergence rate of the proposed collocation Newmark-IGA method and its dependence on the main isogeometric parameters, the mesh size h, the spline polynomial degree p, the spline regularity k, and on the time step size Δt. In addition, a Ricker wavelet propagation test is accurately reproduced. The stability thresholds in time of the proposed method depend linearly on h and inversely on p. Therefore, the proposed collocation Newmark-IGA method retains the good convergence and stability properties of standard Galerkin IGA and spectral element discretizations of acoustic problems, as well as the high computational efficiency of collocation methods due to matrix sparsity and fast function evaluation
Control of flow induced vibrations by means of resonators
Full text linkThis paper focuses on flow-induced acoustic vibrations in piping with closed side branches. These self-sustained oscillations can be very violent, causing an unpleasant or harmful noise. In addition, serious mechanical damages to the pipe supports are possible, due to the consequent mechanical vibrations. Since it is often impossible to completely avoid the problem, it is necessary to resort to strategies in order to mitigate its effects, or by shifting the operating conditions in which they can occur towards different frequencies. This paper deals with the possible use of Helmholtz resonators applied to side branches in order to attenuate noise or to shift the dangerous conditions of resonance. A numerical model is used to study the response of the system in the frequency domain. Initially a side branch with a standard resonator is simulated to highlight the physical phenomena and to study the influence of the main parameters (geometry and position of the resonator). Then some modifications of the simple resonator are proposed in order to increase the dissipation effects in the neck and improve the attenuation of the acoustic vibrations. In particular, the effect of a helical shaped neck and of a composite neck made up of a bundle of narrow ducts is shown. Finally, the potentialities of a double resonator are investigated
NONLINEAR STRESS ANALYSIS PROBLEMS BY SPECTRAL COLLOCATION METHODS
No full textNumerical solutions of nonlinear stress analysis problems are traditionally based on the finite element method. Here, we
introduce a new formulation based on the application of the ‘initial stress’ computational process to the spectral collocation
approximation. We also consider domain decomposition methods in order to handle complex geometries and non-smooth data.
We present several numerical results concerning benchmark problems in geomechanics
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
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