1,720,960 research outputs found
Influence of Core Cellular Structures on Collapse Mechanisms Maps of Sandwich Beams
No full textThe main advantage of 3D printing is manufacturing complex and innovative shapes which guarantee high mechanical properties. Therefore, it is necessary easily figure out the most suitable structure for the required design requirements. The well-known strategy to design sandwich panels is evaluating collapse maps as they determine the panel performances based on their geometrical features. The aim of this study is to update the traditional collapse maps by showing how the core shape can improve the sandwich beam performance. The collapse maps proposed are based on advanced analytical models than the traditional Gibson theories. The analytical modelling of the indentation phenomenon is based on Vlasov’s model. The analytical modelling of the bending phenomenon is based on the First Shear Order Theory. The overall panel stress and strain maps are computed superposing both effects. A composite sandwich panels with Gyroid core based are analyzed to verify the proposed model consistency. A core failure criterion is chosen by experimental testing evidence on the representative core structure. Once the computed stress state overtakes failure criterion ones, the critical load is defined. In the end, the model is exploited to compare the performances of four sandwich panels with cores based on different lattice structure
Combined effect of process variables on the plastic behaviour of 316L stainless steel printed by L-PBF
No full textThe metal additive manufacturing (AM) is a technology that is rapidly spreading in the industrial sector with its enormous potential in making components with complex shapes and low weight, ensuring a high structural strength. However, the mechanical properties of the components depend on the printing process, and the interactions between the process variables and the final material behaviour is still not totally understood. In this work, 12 different types of tensile specimen were built by AM using the laser powder bed fusion (L-PBF) technique; the used material is the 316L stainless steel. The specimens have the same geometry and the same process parameters in terms of layer thickness, hatch space, laser power, spot diameter, scanning speed and platform preheating temperature, while different laser scan strategies and building orientations are evaluated. The scope is to characterize the plastic behaviour of such specimens and study the differences due to distinct printing strategies. Stereo digital image correlation (stereo-DIC) was used to evaluate the deformation state and analyse the material anisotropy. Finally, the microstructure and presence of defects were investigated through the optical microscopy (OM) and the scanning electron microscopy (SEM). The analysis shows how the plastic behaviour and the formation of defects are remarkably influenced by the laser scan strategy and by the building orientation
Integrated Thermomechanical Characterization of Metals Using the Virtual Fields Method
No full textIn this paper, the possibility of characterizing the thermomechanical behavior of metals using the virtual fields method (VFM) and suitable specimens with heterogeneous strain and temperature fields was demonstrated using simulated experiments. The used geometry is a double-notched tensile test with a Gaussian distribution of temperature over the surface. The chosen constitutive model is the Johnson-Cook hardening law coupled with the Hill48 anisotropic yield criterion. First the VFM strategy and the simulated experiments are described. Then the results are presented showing three case studies, (i) only the effect of the temperature is identified, (ii) the whole set of constitutive parameters is identified at the same time, (iii) a two-step identification is performed. The potentiality of the method as well as the main problems are discussed extensively.</jats:p
Effectiveness of remote monitoring of CIEDs in detection and treatment of clinical and device-related cardiovascular events in daily practice: The HomeGuide Registry
No full textAimsThe HomeGuide Registry was a prospective study (NCT01459874), implementing a model for remote monitoring of cardiac implantable electronic devices (CIEDs) in daily clinical practice, to estimate effectiveness in major cardiovascular event detection and management.Methods and resultsThe workflow for remote monitoring [Biotronik Home Monitoring (HM)] was based on primary nursing: each patient was assigned to an expert nurse for management and to a responsible physician for medical decisions. In-person visits were scheduled once a year. Seventy-five Italian sites enrolled 1650 patients [27% pacemakers, 27% single-chamber implantable cardioverter defibrillators (ICDs), 22% dual-chamber ICDs, 24% ICDs with cardiac resynchronization therapy]. Population resembled the expected characteristics of CIED patients. During a 20 ± 13 month follow-up, 2471 independently adjudicated events were collected in 838 patients (51%): 2033 (82%) were detected during HM sessions; 438 (18%) during in-person visits. Sixty were classified as false-positive, with generalized estimating equation-adjusted sensitivity and positive predictive value of 84.3% [confidence interval (CI), 82.5-86.0%] and 97.4% (CI, 96.5-98.2%), respectively. Overall, 95% of asymptomatic and 73% of actionable events were detected during HM sessions. Median reaction time was 3 days [interquartile range (IQR), 1-14 days]. Generalized estimating equation-adjusted incremental utility, calculated according to four properties of major clinical interest, was in favour of the HM sessions: +0.56 (CI, 0.53-0.58%), P < 0.0001. Resource consumption: 3364 HM sessions performed (76% by nurses), median committed monthly manpower of 55.5 (IQR, 22.0-107.0) min × health personnel/100 patients.ConclusionHome Monitoring was highly effective in detecting and managing clinical events in CIED patients in daily practice with remarkably low manpower and resource consumption. © 2013 The Author
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
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