1,720,956 research outputs found
Defects and residual stresses finite element prediction of FDM 3D printed wood/PLA biocomposite
Full text linkThe exploited enthusiasm within the research community for harnessing PLA-based biocomposites in fused deposition modeling (FDM) is spurred by the surging demand for environmentally sustainable and economically viable materials across diverse applications. While substantial strides have been taken in unravelling the intricacies of the process-structure–property relationship, the intricate interdependencies within this context remain only partially elucidated. This current gap in knowledge presents formidable obstacles to achieving the pinnacle of quality and dimensional precision in FDM-fabricated specimens crafted from biocomposites. Despite the existence of numerous numerical models for simulating the FDM process, an unmistakable need exists for models that are custom-tailored to accommodate the distinct characteristics inherent to biocomposites. As a reaction to those pressing needs, this study presents a 3D coupled thermomechanical numerical model designed to predict dimensions, defect formation, residual stresses, and temperature in PLA/wood cubes produced by FDM, considering various process parameters and composite-like nature of wood-filled PLA filaments. The accuracy of the proposed numerical model was validated by comparing its results with experimental measurements of biocomposite cubes manufactured under the same process parameters. Encouragingly, the simulated dimensions showed a maximum relative error of 9.52% when compared to the experimental data, indicating a good agreement. The numerical model also successfully captured the defect formation in the manufactured cubes, demonstrating consistent correspondence with defects observed in the experimental specimens. Therefore, the presented model aims to substantially contribute to the progress in the field of additive manufacturing of PLA-based biocomposites
Numerical prediction of lack-of-fusion defects in selective laser melted AlSi10Mg alloy
No full textDespite the emerging research, it is still troublesome to control the defect formation in selective laser melted parts. In this paper, a mechano-thermo-fluid dynamical FEM model at meso-scale was proposed. The model calculates and predicts the volume and dimensions of lack-of-fusion (LOF) defects according to the applied process parameters. The numerical model was validated with experimentally assessed volume of lack-of-fusion defects and melt pool dimensions. Results shown the lowest volume of LOF defects (0.41%) in specimen produced with 275 W and scanning speed of 400 mm/s. Laser power was determined as a parameter majorly impacting the volume and dimensions of LOF in selective laser melted parts
On the influence of building position on dimensional accuracy and surface quality of aluminum blocks manufactured by L-PBF
Full text linkThe precision of the objects fabricated by laser powder bed fusion (LPBF) and their overall quality is currently commonly increased by process optimization, however the relatively complicated process-structure–property relationship may represent a significant obstacle to its efficiency. This study aims to determine the effects of the position of L-PBF manufactured blocks on the building plate on their geometrical dimensions, tolerances (GD&T) and surface roughness. Within the study, 9 cubical specimens were manufactured from AlSi10Mg powder via LPBF using optimized process parameters, consistent for all the samples, and their GD&T and surface roughness were subsequently analyzed by CMM and perthometer. The system utilized to manufacture the samples was supplied with 200 W Yb-laser with the 90 μm diameter of the laser spot. The fabrication of the blocks and their subsequent GD&T analysis were simulated numerically to further explain the mechanisms of distortion creation. Numerical results were validated by experiments, where the maximal relative error reached 6.88 %. Statistical significance of position on GD&T was demonstrated for dimensional deviations, bottom faces planarity, parallelism of top and bottom faces and perpendicularity of top and x-oriented faces and the regression equations were assessed (with R2 96.30 %, 93.09 % and 99.79 %, 94.54 %, 98.47 %, 99.65 %, and 99.28 %, respectively). The lowest dimensional errors (0.0738 mm in x-, 0.1048 mm in y-, and −0.3844 mm in z-direction) were detected in the block located in the middle of the building plate, which can be reasoned by favorable thermal fields as the specimens are surrounded from all sides by other blocks cumulating heat. Similarly as with dimensional errors, the errors of planarity, parallelism and perpendicularity correlated with the thermal fields over the building platform, resulting in the least distorted cube located in the middle of the base plate
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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