1,720,961 research outputs found
Design and simulation of porous lightweight structures built by selective laser melting
Full text linkI materiali porosi in acciaio sono una classe di materiali alleggeriti che presentano un notevole potenziale in diverse applicazioni che spaziano dal settore automotive a quello aerospaziale. Le proprietà di tale tipologia di materiali sono fortemente influenzate dal tipo, dalla dimensione e dalla distribuzione dei pori in essa presenti. La fusione laser selettiva (selective laser melting o SLM) è una delle più importanti tecnologie di additive manufacturing e consente di controllare in modo appropriato i principali parametri che influenzano il comportamento dei materiali porosi realizzati attraverso tale processo produttivo. Lo scopo del presente lavoro è simulare il comportamento a compressione a temperatura ambiente di provini in acciaio, ottenuti mediante selective laser melting, caratterizzati da pori sferici di grandi dimensioni. Tali strutture rappresentano un concetto di produzione altamente innovativo. La simulazione numerica sviluppata è in grado di coprire l’intero range di deformazione a cui sono soggetti i provini, vale a dire fino al 80% di nominal strain. A tal riguardo, sono stati sviluppati tre modelli agli elementi finiti dei provini sottoposti a compressione uniassiale includendo differenti livelli di dettaglio. Il modello costitutivo selezionato per la realizzazione delle simulazioni agli elementi finiti è il modello di Hollomon e, sebbene i test sperimentali abbiano evidenziato un comportamento altamente non lineare che manifesta il collasso plastico dei campioni porosi, le simulazioni numeriche hanno riprodotto accuratamente i risultati sperimentali. Il presente studio è inoltre in grado di quantificare fenomeni e aspetti caratteristici del comportamento delle architetture porose come, ad esempio, la distribuzione delle tensioni e deformazioni, l’evoluzione dello stress concentration factor in prossimità dei pori e l’effetto dell’aspect ratio dei pori e del comportamento deformativo sulla localizzazione degli stress. Vengono in aggiunta discusse tematiche inerenti la modellazione che contribuiscono a limitare il costo computazionale delle simulazioni pur garantendo un buon livello di accuratezza dei risultati numerici. Infine, nella sezione finale del lavoro si incominciano a porre le basi per le future investigazioni: viene proposto un algoritmo sviluppato “in house” capace di realizzare distribuzioni spaziali di pori sferici al fine di progettare strutture in acciaio caratterizzate da porosità con disposizione random compatibili con le limitazioni imposte dal processo produttivo di fusione laser selettiva.Steel porous materials are multifunctional lightweight materials with a great potential in several applications ranging from automotive to aerospace sector. Their properties are strongly influenced by type, dimension and distribution of pores. Selective Laser Melting (SLM) is one of the most important additive manufacturing technologies, which allows to properly control the main parameters that affect the behavior of manufactured porous materials. The purpose of this study is to simulate the room temperature compression behavior of steel specimens with large spherical pores built via SLM. Such a construction is a highly innovative manufacturing concept. The numerical simulation covers the whole deformation range undergone by specimens, that is up to 80% nominal strain. In this regard, three finite element models of the specimens subjected to uniaxial compression are developed including different levels of detail. The Hollomon model is selected as the constitutive model given in input to the FE simulations. Although experimental tests highlight a highly nonlinear behavior entailing plastic collapse of porous samples, numerical simulations can accurately reproduce experimental results. Moreover, the present study is able to quantify phenomena and characteristic aspects of porous architectures behavior, such as stress–strain distribution, the evolution of stress concentration factor near pores and the influence of pore’s aspect ratio and deformation behavior on stress localization. Modelling issues that may contribute to limit the computational cost of simulations yet preserving good level of accuracy of FE results also are discussed in the article. Finally, bases for future investigations are traced in the last Section of the work: a developed in-house algorithm capable of realizing spherical pores spatial distribution is proposed in order to design steel structures characterized by random porosity compatible with constraints imposed by SLM manufacturing process
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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