1,720,957 research outputs found
Caratterizzazione avanzati di componenti realizzati mediante Material Extrusion
No full textThis work aims to carry out a detailed investigation into the characterization methods of components made by Material Extrusion (MatEx) process. There are several articles in the literature that analyze the influence of process parameters on mechanical properties of MatEx components. However, traditional characterization methodologies are used, and these are not specifically developed for parts made by Material Extrusion process. Due to the layer-by-layer production mode, these components have some specific characteristics that are difficult to evaluate by classical mechanical characterization tests. Thus, advanced characterization of components made by Material Extrusion process has been conducted. Appropriately designed test methodologies have been developed for the mechanical evaluation of such components. Through these tests, the possibility to evaluate some characteristics of components with a high impact on their mechanical properties has arisen. Investigations on the presence of porosity, inter-laminar adhesion, and the impact of the size of manufactured components on their mechanical properties were conducted. Local characterization tests, tests for laminar structures, and process monitoring were the key tools used to evaluate these properties. The selected process parameters during the printing stage and the manufacturing strategies of the samples have been found to have a very high impact on the mechanical properties of the components. From the analysis of the obtained results, it was determined that careful characterization of components produced by material extrusion was needed, through tests specifically designed for such parts
Development of an Instrumented Equipment for Intelligent Resistance Spot Welding
No full textThe present study introduces an instrumented and remotely controlled resistance spot welding machine that enables the intelligent control of the main process parameters. The machine was developed by modifying an existing resistance spot welding machine through interfacing with 'proportional relays,"controlled through an I.O. device and a LabVIEW program. Preliminary welding tests were performed to assess the main machine's capabilities in terms of repeatability, the capacity of control as well as the response time of the equipment. Preliminary tests were conducted to weld low-carbon steel sheets 1.2 mm thick. The tests were conducted by varying the main process conditions, namely the current and the welding time. Other process parameters that contribute to determining the welds' final quality were kept constant during the experiments. Quality assessment of the welds was performed through destructive single-lap shear tests. A dimensional analysis of the welds was also performed
A multidisciplinary approach to investigate the influence of process parameters on interlayer adhesion in material extrusion additive manufacturing
Full text linkThis study investigates the influence of deposition conditions in material extrusion (MEX) on fracture toughness, with a specific focus on the interlayer adhesion. A full factorial experimental design was employed, varying three key parameters: the deposition strategy, the extrusion multiplier, and the extruder speed. Fracture toughness was assessed using double cantilever beam tests, following ASTM D5528 standards. Additionally, the study explores the influence of load direction through various deposition strategies, including 0/90 and ± 45 orientations. To gain deeper insights, real-time thermal analysis was conducted during deposition, utilizing an infrared thermal camera. This allowed to investigate the effect of deposition conditions on temperature history. Subsequent examination of fracture surfaces post-testing was performed using optical and scanning electron microscopy. The findings reveal compelling evidence of the significant impact of the extrusion multiplier, printing speed, and deposition orientation on interlayer adhesion. In addition, the results indicated the presence of crystalline phase after deposition which was due to partially melting during depositions involving high material flow. This was due to the adoption of a semicrystalline filament. The adoption of the multidisciplinary approach enabled a better understanding of some phenomena occurring during the deposition (e.g., formation/existence of crystalline phase) that influence the adhesion behavior. These results underline the capability of such broad approach to analyze the influence of the processing conditions on the interlayer adhesion. Consequently, the developed analysis procedure represents a pivotal approach to study and optimize the MEX process and filament characteristics especially for semicrystalline polymers
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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