1,721,152 research outputs found
Analytical modeling of finite-size elastic metasurfaces: a multiple scattering formulation
No full textHarnessing Temporal Modulation to Achieve Surface-to-Bulk and Frequency Conversion in Elastic Half-Planes
No full textAn analytical approach to model Structure–Soil–Structure Interaction (SSSI) of arbitrarily distributed buildings under SH waves
No full textIn this work, a simplified analytical framework based on the multiple scattering theory is proposed to model the structure–soil–structure interaction of buildings excited by antiplane shear waves. To this purpose, each building is modelled as a single degree-of-freedom oscillator, whereas the soil as a viscoelastic layer laying on an elastic half-space. By neglecting the soil-foundation kinematic interaction and considering only its inertial counterpart, the coupled response of buildings is modelled using a multiple scattering approach, where the buildings scattered wavefields are described via Green’s functions.
The developed analytical framework is exploited to discuss the dynamic response of a single building, evaluating the variation of its amplitude with respect to the characteristic site frequencies. The dynamics of two buildings are then studied by modelling their coupled response. In particular, the interaction between them is investigated as a function of the buildings spacing, mass, and relative stiffness. Finally, the analysis is extended to the coupled response of a cluster of five buildings. Through the discussed examples, it is demonstrated how the proposed methodology can serve as a computationally inexpensive tool for predicting the interaction among vibrating structures under shear antiplane waves propagating at different frequencies
A multiple scattering formulation for elastic wave propagation in space-time modulated metamaterials
Full text linkSpace-time modulation of material parameters offers new possibilities for
manipulating elastic wave propagation by exploiting time-reversal symmetry
breaking. Here we propose and validate a general framework based on the
multiple scattering theory to model space-time modulated elastic metamaterials,
namely elastic waveguides equipped with modulated resonators. The formulation
allows to consider an arbitrary distribution of resonators with a generic
space-time modulation profile and compute the wavefield within and outside the
resonators' region. Additionally, under appropriate assumptions, the same
framework can be exploited to predict the waveguide dispersion relation. We
demonstrate the capabilities of our formulation by revisiting the dynamics of
two representative space-time modulated systems, e.g. the non-reciprocal
propagation of (i) flexural waves along a metabeam and (ii) surface acoustic
waves along a metasurface. Given its flexibility, the proposed method can pave
the way towards the design of novel devices able to realize unidirectional
transport of elastic energy for vibration isolation, signal processing and
energy harvesting purposes
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
- …
