1,720,969 research outputs found
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
Optimalisering av UHPC med redusert sementinnhold
Get PDFSammendrag
Med den raske urbaniseringsveksten øker etterspørselen etter byggevirksomhet samtidig. Betong, som er det viktigste og mest brukte byggematerialet, etterspørres også i store mengder. For å øke fastheten og optimalisere konstruksjonsstørrelsen ble UHPC (Ultra-høyytelsesbetong) utviklet. Denne betongtypen er et relativt nytt materiale som kontinuerlig forskes på. UHPC har utmerket fasthet, både i trykkfasthet (når opp til 200 MPa) og bøyefasthet (når minimum 5 MPa). Dette materialet består av fine bindemidler, hovedsakelig sement, silikastøv og sand. Hele blandingen består av de nevnte bindemidlene tilsatt vann, superplastifiserer og stålfiber. Men materialet medfører en betydelig negativ miljøpåvirkning gjennom høye CO₂-utslipp. For at UHPC skal kunne produsere høy fasthet og kompakte dimensjoner kreves store mengder sement. Det høye sementforbruket skaper de svært høye utslippene.
Reduksjon av CO₂-utslipp i UHPC har vært et av de mest utforskede forskningsområdene. Den mest effektive måten å gjøre dette på er å redusere sementinnholdet i UHPC. Derfor har det vært stort fokus på å finne de mest egnede supplementære sementmaterialene (SCM). SCM er vanligvis avfallsmaterialer eller naturlige materialer som egner seg til betongkomponenter.
Denne masteroppgaven studerer bruken av SCM uten å påvirke (redusere) fastheten til UHPC og samtidig redusere CO₂-utslippene. For å gjøre dette ble to SCM valgt: slagg (erstatning av sementinnhold med 30% og 70%) og kalkstein (erstatning av sementinnhold med 30% og 50%). Det ble gjennomført en serie studier av hvordan disse SCM-ene påvirker UHPC, gjennom laboratorieøvelser og LCA-analyser.
Resultatene viser at de valgte SCM-ene er kompatible med erstatning av sementinnhold. Fra laboratorieøvelsene kunne slagg erstatte 70% av det totale sementinnholdet (og nå nesten 180 MPa), mens kalkstein viste seg å kunne erstatte opptil 30% av sementinnholdet (og nå nesten 176 MPa) i trykkfasthet. I bøyefasthet viser 30% kalksteinerstatning høyeste verdi med nesten 21 MPa. LCA-analysene viste at blandingen med lavest sementinnhold hadde laveste CO₂-utslipp, og reduserte det fra 867 kg CO₂ (for referanse-UHPC) til 502 kg CO₂ (blanding med 70% slagg). Det overordnede resultatet fra studiene viser at bruk av 25% kalkstein som SCM ga høyeste trykkfasthet (182 MPa), og bruk av 10% kalkstein som SCM ga høyeste bøyefasthet (33 MPa).
Resultatene indikerer at UHPC-industrien realistisk kan oppnå 40-60% CO₂-reduksjon gjennom intelligent SCM-implementering, mens ytelseskravene ikke bare opprettholdes, men i mange tilfeller forbedres. Dette representerer et betydelig bidrag til betongindustriens bærekraftsmål og demonstrerer at miljøhensyn og teknisk ytelse ikke nødvendigvis er motstridende målsetninger
Ultra-High Performance Concrete med lokalt grovt tilslag til rehabilitering av brudekker
Get PDFThis master’s thesis focuses on the development and optimization of Ultra-High Performance Concrete (UHPC) mixtures containing local coarse aggregates (0–8 mm) for bridge deck rehabilitation. The primary objective was to identify UHPC recipes that provide an optimal combination of workability and mechanical properties tailored to applications involving inclined surfaces. To achieve this, comprehensive laboratory tests were conducted on mixtures with varying steel fiber contents (2 and 3 vol.%) and adjustments in superplasticizer dosage. Fresh concrete properties such as slump flow, air content, and stability were measured alongside hardened properties including compressive strength, flexural and residual flexural tensile strength, elastic modulus, shrinkage, crack development and chloride ingress. Special emphasis was placed on studying the bond between UHPC overlays and existing traditional concrete substrates to Ensure durable and robust rehabilitation solutions.
The results demonstrate that a UHPC mixture with 2 vol.% steel fibers and carefully controlled additives yields a uniform fiber distribution, good casting consistency and strong mechanical performance. This minimizes the risk of local weakening in sloped bridge decks. The optimized mixture exhibits excellent flow and stability characteristics suitable for demanding casting conditions on inclined surfaces. Additionally, bond tests indicate strong adhesion between the UHPC overlay and the substrate, with failure occurring within the traditional concrete rather than at the interface. This underlines the reliability of the developed UHPC system for bridge rehabilitation. Overall, the thesis provides valuable insights and a foundation for sustainable and functional bridge rehabilitation using UHPC with local materials. The findings contribute to enhancing the understanding of mixture design and execution parameters critical for real-world applications in infrastructure renewal
Styrke og rissutvikling i 3D-printet betong
Get PDFThis master’s thesis was carried out at the University of Agder as part of the MSc in Civil Engineering
program. The aim of the study is to investigate and compare the mechanical properties and crack
development of 3D-printed concrete with reference concrete B45 MF40, which is commonly used in
harsh and chloride-exposed environments. The experiments investigate the effects of print
orientation and reinforcement on the behavior of 3D-printed concrete beams subjected to four-point
bending. The research problem was defined through a literature study, and the following research
question was formulated:
How does the strength and crack development of 3D-printed concrete compare to the reference
concrete B45 MF40?
A total of 24 3DPC and B45 MF40 beams were produced, which include both unreinforced and
reinforced specimens. The 3DPC beams were printed in two orientations (X and Y direction) to study
the anisotropic effects. Four-point bending tests were performed to measure flexural tensile strength
and maximal load capacity. Additionally, digital image correlation was applied to document crack
formation and propagation during testing.
The results showed a clear influence of filament orientation with beams printed in Y-direction
generally demonstrating higher flexural tensile strength than those printed in X-direction. The
flexural tensile strength in both directions was weaker than for the casted specimens. The application
of reinforcement in 3DPC significantly improved crack control and loadbearing capacity, although
optimal bond between reinforcement and concrete remains a challenge as there is a possibility of the
reinforcement moving.
The implementation of reinforcement resulted in higher average point loads for the printed
specimens compared to the cast 3DPC specimens. This suggests that the 3DPC material is not well
suited for casting, and that casting may not be the most appropriate method for evaluating the
material’s true properties. The printed beams showed substantially more concentrated crack
development compared to B45 MF40, where the main cause can be attributed to the fine aggregate
in 3DPC.
The study concludes that 3DPC has the potential to be used as a supplement in structural
applications, particularly in complex geometries and customized components. However, further
development is necessary to optimize printer parameters and reinforcement strategies to fully meet
the strict durability and strength requirements in the construction industry
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
- …
