1,720,957 research outputs found
Misclassification error rejection in structural models for spatial architectures
Full text linkVibration mode pairing via modal coupling and modal assurance criteria is a task encountered in different applications of Structural Health Monitoring. Above these, Sensitivity Analysis, and Model Updating need a correct estimation of the pairing between a reference set of vibration modes (that can be both numerical or experimental) and different sets of numerical vibration modes, generated by the variations of structural model parameters. The incorrect pairing, or coupling, results in error propagation during the sensitivity analysis or model updating, generating biased results. In this paper, the authors propose a reliable and efficient method to reduce the effects of mode pairing (i.e., mode coupling) errors in the calculation of the sensitivity of modal data to mechanical parameter variations, even under complex conditions such as complex numerical models of spatial structures, where the vibration modes are characterized by, for example, high-order mode shapes and high probability of confusing correlated mode shapes. The proposed method is based on the conjunction application of Hilbert-Huang Transform to remove outliers, and Gaussian Mixture Models to alleviate the elimination of meaningful information during the outliers rejection phase. In particular, knowing the actual sensitivity of the vibration modes not only allows to optimize the subsequent automatic model updating phase, but even before that, it allows to optimize the design of a permanent monitoring system, for example by predicting the direction and position of the sensors which maximize the extractable modal information considering that the mechanical parameters are continuously subjected to Environmental and Operational Variations, or again, would allow the optimization of extended experimental campaigns, suggesting additional number of mechanical tests for those structural components which most influence the modal behavior of the structure
Digital Twinning for the Prognosis of Spatial Architectures: Morandi’s Underground Pavilion in Turin
No full textConcrete spatial architecture was mainly built using techniques that at
the time were still experimental and based on design criteria that did not consider
seismic actions. The validity of accurate models accounting for such complex
structural schemes can be demonstrated, but the latter still would not support a
clear comparison with the original predictions.
Different from other Morandi’s balanced beam schemes, in the underground
Pavilion V of Turin Exhibition Center the main post-tensioned ribs are not parallel
beams but are diagonally directed and multiply reciprocally interconnected in
order to obtain a spatial structure offering a high overall rigidity and lateral stability,
and to contrast the instability of the very thin webs of the main ribs.
The paper focuses on how information from the experimental campaign can
help to formulate virtual models for prognostic and diagnostic assessments under
different scenarios, such as for example the design of structural health monitoring
activities and systems
Experimental Design of Bistable Meta-panel for Dynamic Investigation
Full text linkBistable metamaterials offer a promising solution for vibration mitigation in structural systems. This research presents the conceptualization of the experiments for a bistable meta-panel, which uses geometric nonlinearity and snap-through instability to enhance energy absorption and dissipation. A scaled prototype, produced via additive manufacturing, undergoes static and dynamic testing to assess its response. This work provides a foundation for further development of meta-material-based seismic protection systems
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
Simulation and Identification of a Seismic Bistable Device with Hysteresis
Full text linkMechanical metamaterials with bistable configurations offer a promising solution for enhancing energy dissipation in existing structures subjected to dynamic excitations. This research focuses on a pre-buckled steel bistable device engineered for energy dissipation, examining the critical interplay between geometric nonlinearity and hysteretic behaviour. The classical Bouc-Wen model is here modified to incorporate the effects of bistability. The study includes parametric simulations and instantaneous identification of the proposed model parameters. Finally, an equivalent damping factor that considers both viscous and hysteretic dissipation is calculated
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
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