1,720,956 research outputs found
3D Printing: La polvere di ottone prende forma
No full textRIASSUNTO: Il presente lavoro si colloca all’interno delle attività di studio del settore della prototipazione rapida (RP) e si prefigge lo scopo di realizzare semplici componenti metallici (in particolare in ottone), con la tecnica del three dimensional printing (3DP). Il lavoro si articola nelle seguenti parti principali: caratterizzazione dei materiali, polvere di ottone e liquido legante realizzazione di una postazione di lavoro e progettazione dell’interfaccia di controllo tuning dei parametri del processo di printing La prima parte ha per oggetto l’analisi della granulometria della polvere di ottone (per la prima volta impiegata in esperienze di 3DP), lo studio della bagnabilità con il liquido legante selezionato (silice colloidale in glicole etilenico) e la valutazione dell’interazione locale polvere-colla con esperienze preliminari alla stampa inkjet. Il secondo punto riguarda l’assemblaggio di una struttura con guide motorizzate per permettere la movimentazione della testina sul piano di lavoro, lo sviluppo di un circuito con microcontrollore per il pilotaggio (con onda quadra) dell’ugello selezionato, e di un programma che coordina gli spostamenti della testina con il controllo dell’accensione dell’ugello in modo da realizzare la geometria di ciascuna sezione del componente 3D. La parte finale coinvolge le numerose esperienze sperimentali sul perfezionamento del sistema e sull’ottimizzazione dei parametri in particolare prima con stampe con inchiostro su carta e metallo per studiare l’influenza del segnale elettrico sulle caratteristiche (forma, dimensioni, velocità) delle goccioline espulse dall’orifizio, successivamente con stampe con liquido legante sul letto di polvere in modo da caratterizzare la linea primitiva, la sezione, il modello 3D. SUMMARY: This work has been carried out within the framework of the rapid prototyping (RP) systems studies and has the aim to build simple metal components (particularly brass) with the technique of the three dimensional printing (3DP). The thesis is divided into the following main parts: characterization of the materials (brass powders and binder) realization of a workbench and developing of a control interface tuning of the printing parameters The first part is related to the particle-size analysis of brass powders (for the fist time employed in 3DP experiences), the study of the wet ability of the selected binder fluid (Colloidal silica in Ethylene glycol) and the evaluation of the interaction grain-binder with preliminary tests before printing with the inkjet-head. The second part regards the assembly of a structure with motorized guides in manner to consent the moving of the head on the workspace, the development of a circuit with microcontroller for the activation (with PWM signal) of the selected nozzle, and of the control program to coordinate the moving of the inkjet-head with the control of the firing of the nozzle in order to realize the desired geometry of each section of the 3D component. The final part deals with the several experimental experiences about the improvement of the system and the optimization of the parameters in particular before with ink printing on paper and metal to study the influence of the PWM signal on the characteristics (size, form, speed) of the droplets produced by the orifice, next with printing with binder on the powderbed in order to characterize the primitive line, the section, the 3D model
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
