1,720,957 research outputs found
Micro injection moulding process with high-temperature resistance resin insert produced with material jetting technology: Effect of part orientation
No full textMaterial jetting is an additive manufacturing technology used to produce resin parts with high accuracy and good surface finish. It is often used for visual prototypes or for rapid tooling applications to realise moulds for the standard injection moulding process because of the mechanical properties of the material. However, owing to the poor thermal properties of the resin, this technology is limited by the melting temperature of the material and the production rate. Currently, newer resins are able to withstand temperatures up to 250 °C. To enhance the potential of this technology, in this study the authors tested the performance of a mould insert for microinjection moulding application, produced with a high-temperature resin. In particular, it has been analysed how the orientation of the mould insert on the build plate significantly affects the insert resistance and surface roughness and consequently the quality of the moulded part. The results obtained open up new possibilities for testing a series of small batches and highlight new challenges to improve the process performance
Investigation of the micro-milling process of steel with THz bursts of ultrashort laser pulses
No full textBurst mode (BM) processing with femtosecond laser pulses is emerging as a versatile tool for manufacturing micro-components on different materials, thanks to its ability to reduce the thermal load, which ensures highly precise and accurate miniaturization. However, a systematic investigation of the influence of the experimental parameters introduced by such irradiation mode, i.e., the number of pulses within the burst, their polarization and the intra-burst frequency, on the ablation process has not been reported, yet. In this work, we exploited a statistical approach based on the Design of Experiment (DoE) to study the micro-milling process of steel with bursts. Two prediction models were defined, describing the relationship between the working parameters, i.e., average power, number of overscans, laser repetition rate, scan speed and number of pulses within the bursts, and the response variables, i.e., ablated depth and surface roughness, revealing burst mode as a very promising solution to improve the surface finishing of ultrashort laser pulses micromilled components
Study of rheological behaviour of polymer melt in micro injection moulding with a miniaturized parallel plate rheometer
Full text linkThe study of the rheological behaviour of the polymer in micro cavities is one of the aspects related to the technology of micro injection moulding (μIM) still substantially unresolved. Even today, there are no databases on the rheological characteristics of the material specific for the μIM, which, therefore, takes into account a number of important differences compared to the conventional injection moulding. In this paper, the study of the rheological behaviour of the polymer melt in a thin plate cavity with variable thickness has been conducted. The use of a micro injection moulding machine, on which the prototype of a sensorized mould with pressure and temperature sensor has been mounted, allowed the rheological study of the material under high shear rate conditions. After preliminary tests on different thicknesses, it has been studied the viscosity of polymer melt for 400 μm thickness. The viscosity reduction observed meets the characteristics of a pseudoplastic fluid subject to shear thinning and the wall slip seems to play an important role in the apparent reduction of viscosity. The results suggest to increase injection speed, and consequently injection pressures, so that the reduced viscosity can help melt flow to overcome the extreme conditions due to the aspect ratio and to obtain greater efficiency from the filling phase against the high cooling rate typical of micro injection moulding
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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