1,720,955 research outputs found
Experimental and Numerical Characterisation of the Mechanical Properties of the Titanium Alloy-lightweight Concrete Interface
Get PDFQuesta tesi affronta la possibilità di utilizzare il titanio come materiale alternativo per il rinforzo del calcestruzzo dal punto di vista del comportamento di interfaccia che i due materiali sviluppano quando sono combinati in un materiale composito strutturale. A tal fine sono stati condotti diversi programmi sperimentali: prove di sfilamento (pull-out) di barre lisce in lega di titanio Ti6Al4V da provini di calcestruzzo di peso
normale (NWC) e alleggerito (LWC); prove di pull-out di fibre in Ti6Al4V dritte ed uncinate alle estremità da provini in LWC; prove di flessione su tre punti su provini e su una trave di dimensioni realistiche in calcestruzzo alleggerito fibrorinforzato con fibre di titanio (TiFRC). L’ultimo programma sperimentale è volto alla caratterizzazione della resistenza alla frattura e alla quantificazione dell’effetto scala sulla resistenza a flessione. Le prove di pull-out sono state supportate dall’analisi numerica. I risultati dei test condotti sulle barre in lega di titanio, coadiuvati da analisi al microscopio elettronico (SEM) e ottico, hanno evidenziato che, nonostante le barre impiegate siano lisce, il processo di sfilamento è influenzato dalla formazione di asperità all’interfaccia, dovuta prevalentemente alla presenza di materiale matriciale residuo sulla superficie delle barre. La rottura di tali asperità genera un ingranamento meccanico a livello microscopico, a sua volta responsabile del comportamento dilatante dell’interfaccia. Per descrivere numericamente questo processo è stato formulato un nuovo modello coesivo definito enhanced degrading M-CZM, che tiene conto dell’azione di danno, attrito, ingranamento meccanico e dilatanza. Con tale modello, sono state condotte analisi di sensitività e una procedura di identificazione per riprodurre i risultati sperimentali delle prove di pull-out delle barre. Un’ulteriore validazione del modello è stata ottenuta simulando numericamente le prove di sfilamento delle fibre dritte.The possibility to use titanium as alternative reinforcement for concrete is investigated in this thesis by focusing on the interfacial behaviour that the two materials develop when they are combined in a composite structural material. To this end, several experimental programs were conducted. The first one concerns the pull-out behaviour of plain bars made of the titanium alloy Ti6Al4V from two different concrete mixtures, i.e. Normal and Light Weigh Concrete (NWC and LWC, respectively). The second experimental program investigates the pull-out behaviour of Ti6Al4V straight and hooked-end fibres from LWC specimens. The third and last series of experiments regards the fracture toughness characterisation of a fibre reinforced concrete material made of LWC and titanium fibres (TiFRC). A series of specimens and a full-scale beam made of TiFRC, without any other reinforcement, have been built and tested under three-point load conditions in order to measure the size effect on the flexural strength. The experimental results concerning the pull-out tests are supported by Finite Element (FE) analyses. Particularly, the results of the bar pull-out tests, combined with Scanning Electron Microscope (SEM) analyses, show that, although the employed rebars are plain, the debonding process is strongly affected by defects-induced surface roughness present at the microscopic level, which activates mechanical interlocking responsible for the dilatant behaviour of the interface. A novel cohesive zone model micromechanics-based formulation is implemented in the FE model in order to account for such aspects. The introduced enhanced degrading M-CZM, accounting for damage, friction, mechanical interlocking and dilatancy, is used to carry out sensitivity analyses and identification procedures on the FE models simulating the bar pull-out tests. The proposed modelling strategy is further validated by performing FE simulation of straight fibres pull-out tests
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
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