1,720,966 research outputs found
Treed gaussian process for manufacturing imperfection identification of pultruded GFRP thin-walled profile
No full textThe process of manufacturing pultruded FRP (Fiber Reinforced Polymers) profiles involves unavoidable imperfections that affect their structural performances. This is is even more relevant for the stability of axially loaded slender elements, due to the importance of imperfections and notches to initiate the buckling phenomenon. Thus, they become a predominant factor for the design of lightweight FRP beam-like structures. A Bayesian approach is proposed to estimate the presence and location of manufacturing imperfections in pultruded GFRPs (Glass Fiber Reinforced Polymers) profiles. Specifically, the Treed Gaussian Process (TGP) procedure is applied. This approach combines regression Gaussian Processes (GP) and Bayesian-based Recursive Partitioning. The experimental and numerical modal shapes of wide flange pultruded profile were investigated. The experimental data were compared with the numerical results of several Finite Element Models (FEM) characterised by different crack sizes
Recursive partitioning and Gaussian Process Regression for the detection and localization of damages in pultruded Glass Fiber Reinforced Polymer material
Full text linkIn this paper, a methodology for the detection and localization of damages in composite pultruded members is proposed. This is particularly relevant to thin-walled pultruded members, which are typically characterized by orthotropic behavior, anisotropic along the fibers and isotropic in the cross section. Hence, a method to detect and localize damage, and the influence these might have on the performance of thin-walled Glass Fiber Reinforced Polymer (GFRP) members, is proposed and applied to both numerical and experimental data. Specifically, the numerical and experimental modal shapes of a narrow flange pultruded profile are analyzed. The reliability of the proposed semiparametric statistical method, which is based on Gaussian Processes Regression and Bayesian-based Recursive Partitioning, is analyzed on a narrow flange profile, artificially affected by sawed notches with incremental depth. The numerical investigation is carried out via finite element models (FEMs) of the cracked beam, where the dynamic parameters and the modal shapes are computed. In total, three different crack sizes are investigated, to compare the results with the experimental ones. Finally, the proposed approach is further extended and validated on numerically simulated frame structures
Preliminary analysis of ambient vibration tests of an ancient renaissance palace after 2012 Emilia earthquake in northern Italy
No full textIn-plane behaviour of NFRCM-strengthened masonry modelled by means of discrete elements
No full textIn the last years, the attention to the use of eco-compatible materials and the development of sustainable solutions for structural strengthening has increased, leading to fibre-reinforced cementitious matrices (FRCM) made by natural fibres (NFRCM, de Carvalho et al. 2017).
NFRCM strengthening systems, in the same manner as FRCM ones, can be considered an alternative to fibre-reinforced-polymer (FRP) reinforcement for masonry structures, to improve the compatibility of reinforcement applied to masonry substrate (di Tommaso et al. 2017).
The numerical assessment of NFRCM and/or FRCM strengthened masonry is an active field of research and it represents a complex task, due to the complexity of both reinforcement and support materials, which can be considered as composite ones. In literature, some macro-models consider both masonry components (bricks and mortar) as a homogeneous continuum, and FRCM layers are considered as an additional equivalent continuum, with the textile fibres assumed as an embedded reinforcement of mortar matrix (Wang et al. 2017). These models have been extended to NFRCM (de Carvalho et al. 2019).
Recently, a simplified micro-model approach was proposed for diagonally loaded masonry panels reinforced with FRCM (Murgo et al. 2021), adopting a 2D FE model with one-dimensional interfaces for masonry panels, and adding a bi-directional grid of trusses for representing the reinforcement.
An updated discrete element model for simulating the in-plane behaviour of masonry walls strengthened with FRCM or NFRCM has been recently introduced by authors (Baraldi et al. 2021). This model is based on an existing discrete or rigid block model having rigid elements and nonlinear one-dimensional interfaces between them, able to represent both mortar joints and brick cracking (Baraldi et al. 2020). Such a model has been improved by considering masonry strengthened on both sides The hypothesis of perfect adhesion between the wall and reinforcement and also between the matrix and fibres of the strengthening system is assumed, in order to avoid the increase of model degrees of freedom with respect to the unreinforced masonry (URM) case. The reinforcement is modelled by means of further stiffness and strength parameters accounting for the FRCM/NFRCM geometrical and mechanical properties.
The proposed model has already turned out to successfully simulate cracking both on masonry and the external reinforcing layers and it was calibrated with respect to an existing simplified numerical model (de Carvalho et al. 2019).
In this work, the proposed discrete model is calibrated and compared with respect to several existing laboratory tests of in-plane loaded masonry panels reinforced with FRCM and NFRCM layers, in order to highlight its effectiveness and potential improvements
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
- …
