1,721,574 research outputs found
Specification of Concrete Strength According to ČSN EN 13791 (2020)
No full textNová norma ČSN EN 13791 (2020) uvádí postupy stanovení charakteristické pevnosti betonu v existujících konstrukcích na základě zkoušek vzorků odebraných z konstrukce. Příspěvek zdůrazňuje význam testování odlehlých hodnot a kriticky hodnotí postupy odhadu charakteristických pevností podle ČSN EN 13791 a základního Eurokódu ČSN EN 1990. Postup podle ČSN EN 13791 je částečně statisticky nepodložený, a proto se doporučuje jej plně harmonizovat s obecnými zásadami ČSN EN 1990.New standard ČSN EN 13791 (2020) provides the procedures for estimating the characteristic strength of in-situ concrete using cores specimens. The submitted contribution reviews the testing of outlying observations and compares the estimation in accordance with ČSN EN 13791 and ČSN EN 1990. It is shown that the approaches in ČSN EN 13791 are only partly based on the principles of mathematical statistics and it is recommended to harmonize fully the estimation with the procedures in ČSN EN 1990
Evaluation of concrete strength according to standard PN-EN 13791
No full textNormę PN-EN 13791:2008 wprowadzono w Polsce ponad rok temu. Nowe, bardziej tolerancyjne, elementy ocen wytrzymałości betonu mogą prowadzić do trudności interpretacyjnych. Dotyczy to określania klasy wytrzymałości betonu na podstawie odwiertów rdzeniowych, przy jej wyznaczaniu szczególną rolę odgrywa dzielnik korygujący o wartości 0,85, podnoszący automatycznie dotychczasową klasę betonu o jeden stopień. W artykule zamieszczono przykład ilustrujący ten problem związany z budową wiaduktu w obwodnicy Kraśnika.After over one year practice with EN 13791 in Poland some critics concerning its discrepancies strongly arisen when was applied to concrete bridge diagnosis were discussed. The special attention has been paid onto the role of 0,85 introduced divisor, valid when one runs from in-situ compressive strength to compressive strength class. The disputation has been supported by concrete caring-deck investigation results of nearby Kraśnik located over-gorge bridge
EN 13791 ter discussie. Een vergelijking van de bepaling van f' volgens NEN-EN 13791 en NEN-EN 1990
No full textVoor de bepaling van de karakteristieke waarde van de betonclruksterkte van een gerealiseerde betonconstructie wordt in de praktijk gebruikgemaakt van NEN-EN 13791 . Het toepassingsgebied van deze norm richt zich vooral op het vaststellen van de karakteristieke waarde van de betondruksterkte in geval van twijfel over de gerealiseerde sterkte. Daarom is de norm niet zonder meer geschikt voor het beoordelen van de constructieve veiligheid van betonconstructie
Nowe podejście do oceny wytrzymałości betonu w konstrukcji istniejącej wg PN-EN 13791:2019-12
No full textZaktualizowana w grudniu 2019 roku norma PN-EN 13791 wprowadza gruntowne zmiany w zasadach oceny wytrzymałości betonu w konstrukcji. W tym artykule przedstawiono zagadnienia dotyczące oceny betonu w konstrukcjach istniejących. Zwrócono uwagę na bardziej precyzyjne zasady dotyczące wyznaczania miejsca pomiarowego i koniecznych w jego obrębie punktów pomiarowych. Precyzyjniejsze są również zasady szacowania wytrzymałości betonu w konstrukcji. W podsumowaniu zestawiono główne różnice pomiędzy starą i aktualną wersją normy.Updated in December 2019, the PN-EN 13791 standard introduces profound changes in the rules for assessing the strength of concrete in construction. This article presents issues regarding the assessment of concrete in existing structures. Attention was drawn to more precise rules regarding the determination of the test region and necessary test location points within it. The rules for estimating the strength of concrete in a structure are also more precise. The summary contains the main differences between the old and the new version of the standard
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
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