1,720,965 research outputs found
Structural Health Monitoring for Performance Assessment of Bridges under Flooding and Seismic Actions
Full text linkBridges can be subjected to damaging environmental actions due to flooding and seismic hazards. Flood actions that result in scour are a leading cause of bridge failure, while seismic actions that induce lateral forces may lead to high ductility demand that exceeds pier capacity. When combined, seismic actions and scour can lead to effects that depend on the governing scour condition affecting a bridge. Loss of stiffness under scour can reduce the ductility capacity of a bridge but can also lead to an increase in flexibility that may reduce seismic inertial forces. Conversely, increased flexibility can lead to deck collapse due to support loss, so there exists some uncertainty about the combined effect of both phenomena. A necessary step towards the performance assessment of bridges under flooding and seismic actions is to calibrate numerical models that can reproduce structural responses under different actions. A further step is verifying the achievement of performance goals defined by codes. Structural health monitoring (SHM) techniques allow the computation of performance parameters that are useful for calibrating numerical models and performing direct checks of performance goal compliance. In this paper, various strategies employed to monitor bridge health against scour and seismic actions are discussed, with a particular focus on vibration-based damage identification methods
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
Mid-latitude Ionosphere Variability (2013–2016), and Space Weather Impact on VTEC and Precise Point Positioning
No full textThe dominant error source for Global Navigation Satellite Systems (GNSS) is the ionosphere, especially during strong solar activity and space weather. Using dual-frequency GNSS observations, the integral of the electron density along a GNSS signal in the ionosphere can be estimated. For research and practical applications, this is usually mapped to the Vertical Total Electron Content (VTEC). VTEC is used to study and monitor the ionosphere, and correct ionosphere effects that degrade the accuracy and reliability of GNSS positioning. For the first time, this paper represents detailed study of the VTEC variability for Bosnia and Herzegovina by analyzing daily, monthly, seasonal, solar cycle and space weather-related VTEC variations for a 4-year period, i.e. from 2013 to 2016. VTEC values were derived from GNSS observations of the EUREF Permanent Network (EPN) station SRJV, located in Sarajevo (43.8679N, 18.4139E). VTEC varied according to solar activity and solar cycle progression. The largest VTEC values and standard deviations occurred during spring equinox. Moreover, ionospheric winter anomaly was observed during high solar activity. Furthermore, the impact of a severe St. Patrick’s geomagnetic storm in March 2015 was studied in terms of VTEC variations and dual-frequency Precise Point Positioning (PPP). During a storm, VTEC values change from about 50% to 150% with respect to the mean VTEC of quiet days. Artificial coordinate variations were visible in all three components (north, east and up), where the highest position error was up to 0.2 m in the up component
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
Earth Rotation and Its Parameters
No full textThe Earth is under continuous influence of external attractive forces of the Sun and Moon, as well as an internal coupling between the Earth’s core and mantle and mass movements. This is why its rotation is not uniform. The direction of its rotation vector experiences long-term and periodic changes w.r.t. a space-fixed reference system (precession and nutation), as well as changes w.r.t. the Earth-fixed reference system (polar motion). Fluctuations in the Earth’s rotation speed are known as length of day (LOD) variations. Precession, nutation, polar motion, and length of day are together called Earth orientation parameters (EOP). They are the link between the celestial and terrestrial reference frames, and therefore, crucial in the transformation between them. This paper introduces the reader to the variable Earth rotation and the driving forces acting behind it, as well as the corresponding EOPs and reference frames. It gives a brief historical overview on latitudinal observations, and how they impacted the establishment of the today-known IERS (International Earth Rotation and Reference Systems Service). Furthermore, a description on the currently used techniques for the determination of EOPs is given at the end of this work, continuing with an example of utilizing GNSS observations for the determination of Earth rotation parameters (ERP)
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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