1,721,190 research outputs found
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
Why data on frailty and SARS-CoV-2 infection are basic to progress
No full textSeveral studies showed that frailty was a predictor of in-hospital death in older adults with COVID-19. The mechanisms through which frailty increases the severity of COVID-19 are several, including immunosenescense and dysregulated inflammation. Whether individuals affected by frailty exhibit a higher susceptibility to SARS-CoV-2 infection remains an open question. Here we report the case series of 40 older persons that in February 2020, before the first case of COVID-19 was detected in Italy, went together on a winter holiday. Back home, 7 of them developed influenza-like symptoms and one was hospitalized due to COVID-19 pneumonia. Between May and July, the seniors were offered the possibility to be tested for SARS-CoV-2 antibody positivity. Twenty-seven of them accepted: 13 had a positive serological test whereas no active infection was found. Comparing the characteristics of those who tested positive and the others, we found that the former group was frailer, exhibiting higher Clinical Frailty Scale scores
Predicting buckling resistance of two three-dimensional lattice architectures
Full text linkLattice structures are an important class of architected cellular solids and structures with high potential for multifunctional and lightweight applications. Novel technologies such as additive manufacturing have vastly extended the design freedom to develop such architectures. In this work, a reliable theoretical model for optimizing unit cell design against buckling is developed for two different cell architectures: pyramidal and tetrahedral. The model's accuracy was evaluated through extensive finite element analysis and compared to existing methods available in the literature
Enhancing the Robustness of Hybrid Metal-Composite Connections Through 3D Printed Micro Penetrative Anchors
Full text linkThis work proposes a novel solution for manufacturing hybrid metal-composite joints, in which different pin shapes are evaluated for their capability to penetrate long carbon fiber epoxy composites successfully and for the mechanical behavior determined by each configuration. On the metal side, pins are manufactured by Laser Powder Bed Fusion (LPBF), downsizing the currently adopted solutions and, at the same time, developing new blocking features aimed at enhancing the mechanical properties of the joint. The different configurations were evaluated in two distinct experiments: the first to evaluate the induced defects in the composite substrate and the second to characterize the mechanical behavior of the joint. It emerges that smaller pins produce much less damage and misalignments in the composite structure with respect to the conventional pin solution, whereas the new “blocking features” configurations consistently increase maximum pullout load and energy with respect to the conventional pin solution, with the same level of fiber damage
Probabilistic first-ply failure analysis of a symmetric-equilibrate laminate in composite material
No full textA general procedure to develop a probabilistic analysis of composite materials is presented. The second order of the Taylor series was used to determine the statistics of the first ply failure for a symmetric equilibrate composite. The Monte Carlo Method was used to validate the accuracy of the procedure
Applicazione di metodi numerici con utilizzo di immagini digitali per l’analisi delle tensioni residue in lamiere rivestite mediante smalto porcellanato
No full textThe effect of morphology on poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene)-based soft actuators: Films and electrospun aligned nanofiber mats
Full text linkThis paper analyzes soft actuators realized as unimorph cantilever beams, in which the active layer can have two different morphologies, i.e., either an extruded film or an aligned electrospun nanofiber mat of the poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene). Six different soft actuators are fabricated, with active layers of varying thicknesses and morphologies, to study the electrostrictive effect of the polymer and to evaluate the stiffening properties, the mechanical work, and the blocking forces of the actuators when stimulated by different direct current electric fields. The comparison between the different actuators is performed by introducing weight specific properties, i.e., specific stiffness and specific work, showing improved specific properties for the nanofibers-based actuators. Moreover, the blocking forces, the tip deflections, and the leakage currents of the actuators are evaluated when stimulated by alternating current electric fields. The experiments show faster viscoelastic relaxation and lower electrical power consumption for the nanofibers-based actuators. This study concludes that, thank to its electro-mechanical properties, the poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) in the form of aligned electrospun nanofiber mat has high potential to be used as the active layer of electrostrictive unimorph beam soft actuators
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