1,720,981 research outputs found
Mechanical behaviour of timber joints with slotted-in steel plates
No full textTimber joints are a key part of timber structures. Their reliable performance is a prerequisite to successful timber construction. The structural loadbearing behaviour of timber joints is mechanically complex and difficult to predict. Although numerical tools are currently available, these do not consider all anisotropic aspects of timber. However, to predict performance of a timber joint with useful accuracy a 3D material model need to be taken into account in the calculation of the global load-slip behaviour. The research reported in this thesis describes a newly developed 3D material model based on the concepts of continuum damage mechanics. Furthermore, it describes experiments on hardwood timber joints using dowels with different steel grades. Finally, it compares the calculated mechanical behaviour (based on the developed 3D model) with the experimental results. Betrouwbare houtverbindingen zijn essentieel voor houtconstructies. Het mechanisch gedrag van een houtverbinding onder verschillende belastingen is echter complex en laat zich moeilijk voorspellen. De huidige rekenmodellen nemen de anisotropische aspecten van hout niet volledig in beschouwing. Om de sterkte van een houtverbinding te voorspellen is het echter noodzakelijk een 3D materiaalmodel toe te passen in de berekening van het kracht-verplaatsingsgedrag. In dit proefschrift wordt een 3D materiaalmodel voor toepassing op houtverbindingen beschreven. Daarnaast worden de experimenten beschreven die zijn gedaan op loofhout verbindingen met stalen stiften met verschillende materiaalkwaliteit. Het voorspelde mechanische gedrag (gebaseerd op het ontwikkelde 3D model) wordt vervolgens vergeleken met de resultaten van de experimenten.Structural EngineeringCivil Engineering and Geoscience
Dreidimensionales nichtlinear-elastisches materialmodell für holz unter berücksichtigung der schädigung
No full textEin holistisches konstitutives Modell für das Material Holz wurde entwickelt, das das dreidimensionale Verhalten mit duktilen Versagensmechanismen bei Druckbelastung und sprödem Versagen bei Zug- und Schubbelastung sowie die großen Festigkeitsunterschiede in den einzelnen Materialrichtungen abbilden kann. Das Modell basiert auf Ansätzen der Schädigungsmechanik, die die Spannungs-Dehnungsbezie- hungen nach dem Erreichen der Elastizitätsgrenze mit nichtlinearelastischen Algorithmen beschreiben. Das Material Holz wurde als orthotropes Kontinuum modelliert mit einzelnen Schädigungsparametern für die definierten Versagensarten. Die Versagenskriterien, die die Elastizitätsgrenzen bestimmen, formen keinen einfachen Versagenskörper im Spannungsraum, sondern sind stückweise definiert; der 6D Versagenskörper setzt sich also aus unterschiedlichen Körpern zusammen. Die Schädigungsparameter können in der Auswertung angezeigt werden. Somit kann eine zunehmende Faserstauchung bei Druckbelastung in Faserrichtung ebenso identifiziert werden wie bspw. eine Risszunahme im zugbeanspruchten Bereich. Das Modell wurde als Subroutine in ein bestehendes FE-Programm eingebaut und zur Modellierung von Lochleibungsversuchen und zweischnittigen Verbindungen mit Stabdübeln unter Verwendung unterschiedlicher Holzarten eingesetzt. Die Modellierungsergebnisse zeigen deutlich eine zunehmende Schwächung der Querrichtungen durch lokales Entfestigungsverhalten bei zunehmenden Verformungen, während das globale Lochleibungs- oder Verbindungsverhalten duktil bleibt. Das Modell ist in der Lage, beobachtete Versagensmechanismen abzubilden. Ein großes Problem bleibt die Verfügbarkeit von benötigten Materialparametern für die Steifigkeit und Festigkeit sowie die Entfestigung. Dies gilt besonders für selten untersuchte Holzarten wie tropisches Hartholz, die jedoch sehr wohl in der Praxis verwendet werden.Structural EngineeringArchitectur
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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