1,721,039 research outputs found
Mesoscale Modeling of Chloride Penetration in Unsaturated Concrete Damaged by Freeze-Thaw Cycling
Get PDFFor concrete structures exposed to frost attack, cracks, or microcracks induced by freeze-thaw cycling can format interconnecting flow paths and allow more water or chloride ions to penetrate into the bulk concrete. It will subsequently facilitate further deterioration of concrete structures and accelerate the corrosion of embedded reinforced steel bars. Moreover, in reality most concrete structures are rarely fully saturated, so that chloride transportation in unsaturated concrete must be studied with respect to the water moving process in order to cover the real existing service conditions. In the current work, a numerical simulation method based on the mesoscale composite structure of concrete, named the lattice network model, is established to analyze the penetration property of concrete; especially the effects of microcracking induced by freeze-thaw damage on the unsaturated flow behavior are investigated. In the mesoscale model, concrete is treated as a three-phase composite material consisting of coarse aggregates, mortar matrix, and interfacial transition zone (ITZ) between the aggregate and the mortar matrix. The diffusivities of each phase, (i.e.,water and chloride diffusion coefficients) is separately characterized and quantified in terms of the published test results. The unsaturated flow theory for capillary water absorption and chloride transport is employed to simulate the ingress of water and chloride ions into concrete. It is found that the water absorption and chloride penetration are substantially influenced by the frost action, and the cumulative absorbed water and chloride penetration depth are increased with the increase of freezing-thawing cycles (FTCs). Furthermore, the numerical predictions about water absorption and chloride profiles are compared with the experimental measurements. The comparisons indicate that numerical predictions agree very well with the test data
In-Plane Shear Performance of Masonry Walls after Strengthening by Two Different FRPs
Get PDFThis experimental study was aimed to investigate the in-plane shear performance of externally strengthened masonry walls using two types of fiber-reinforced polymer (FRP) sheets, namely, carbon FRP (CFRP) and polyethylene terephthalate-FRP (PET-FRP) sheets. Among these two, PET-FRP has a low tensile strength but possess a higher fracturing strain than CFRP. Twelve masonry walls made from clay brick were tested for static lateral loading under constant compression, after bonding CFRP and PET-FRP sheets onto their surfaces in three different configurations. The ultimate shear strength and deformation at peak load were the two important observations. The mechanisms by which load was carried were observed, varying from the initial uncracked state to the final, fully cracked state. The results demonstrate that a significant increase in the in-plane shear capacity of masonry can be achieved by bonding these two FRPs to the surface of the walls but ductility is compromised when CFRP is used. Walls retrofitting with PET-FRP in a crossdiagonal fashion show a good ductile behavior in both prepeak and postpeak regimes. The experimental data were used to assess the effectiveness of the strengthening of one FRP over the other. PET-FRP in diagonal configuration was found to be the most effective way of strengthening without compromising the two most essential aspects of masonry, that is, strength and ductility
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
Enhancement of the concrete-PCM interfacial bonding strength using silica fume
Get PDFRecently, the polymer cement mortar (PCM) overlaying method has gained popularity as a repair/retrofitting technique. The debonding issue at the interface hinders the worldwide application of this strengthening method. Accompanying the occurrence of debonding at the interface, the strengthening effect of the PCM is lost, causing a sudden decrease in the load-carrying capacity. To prevent premature debonding, this study aims to enhance the concrete-PCM interface by using silica fume. The bi-surface shear test was selected as the test method, and three levels of surface roughness (highest level with sandblasting, medium and lowest levels with steel wire brushing) and two different concrete compressive strengths (low strength type (LS) with 16.73 MPa and normal strength type (NS) with 29.59 MPa) were given as experimental parameters. When the surface is roughened by sandblasting, the specimens with 5% silica PCM increase the interfacial strength compared to that of the normal PCM cases by approximately 36.84% and 35.05% for the "LS" and "NS" types of concrete, respectively. The percentage increase is even higher when the surface is roughened by steel wire brushing (high and low), with an increase of approximately 135.35% and 181.12%, respectively. This fact indicates that silica fume inclusions can enhance the chemical bonding at the concrete-PCM interface. The mixing of silica fume in PCM and a higher surface roughness level shifts the pure interface failure (I) mode closer to the concrete cohesion (C) failure mode for "LS" type concrete and to the composite fracture mode (I-P) for "NS" type concrete. Conclusively, it is confirmed that mixing silica fume into PCM strengthened the interface bonding strength
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