1,721,013 research outputs found
Floodplain hydrodynamics and connectivity in a natural compound channel during unsteady flow events
No full textThis study investigates the hydrodynamics features and the floodplain connectivity of a natural compound channel under unsteady flood conditions using a two-dimensional shallow water equation model and a Lagrangian particle tracking method. Two flood events in 2019 in the middle reach of the Ganjiang River in China were simulated. The results show that during the rising stage, flow first passed through the low-lying areas of the floodplain. The floodplain discharge ratio increased almost linearly with the depth ratio between the floodplain and main channel when the floodplain was not fully inundated. When the floodplain was fully inundated, a second linear relationship was found between the floodplain discharge ratio and depth ratio. During the falling stage, flow first moved back to the low-lying floodplain and main channel before fully receding from the floodplain. The sequence of peak velocity, discharge and stage in unsteady flow lee to higher velocities, lower depths, and shorter residence times during the rising limb compared to those in the falling limb at the same discharge. The threshold discharge for floodplain inundation was during the rising stage larger than during the falling stage. The shortest particle residence time was observed at the flood peak, while the residence time in the rising stage was longer than in the falling stage. The particle travel distance was similar at different stages. The exchange flux between the river and floodplain increased with inflow discharge following a power law relationship. The ratio of exchange flux to inflow discharge also increased with inflow discharge up to an upper limit of 65.5 %. Particle residence time was negatively correlated with discharge following a power law with a lower limit of 2630 s, while particle travel distance is positively correlated with discharge following a power law with an upper limit of 2325 m. These findings shed light on the complex hydrodynamic processes and connectivity patterns in natural compound channels during unsteady flood conditions
Hydraulic complexity at a laboratory-scale confluence: Experimental distribution of bioenergetics metrics and its relation to Yangtze finless porpoise habitats
No full textConfluences are key features in river networks and serve as critical nodes for ecological patterns, often exhibiting rich biodiversity. However, our current understanding of how hydrodynamics influences these patterns remains limited, as most previous studies have focused on ecological factors alone. This study applied a Particle Image Velocimetry system to investigate the spatial distribution of hydraulic complexity metrics (M1, M2, and M4) in a laboratory-scale confluence under both steady and unsteady flow conditions. These metrics, derived from velocity measurements, have been applied in previous studies to characterize aquatic species abundance, richness, and motion. M1 was found to effectively delineate the different hydrodynamic zones of the confluence, peaking within the shear layer. Additionally, M1 can identify the boundary areas with steep velocity gradients inside the separation zone. Field observations of finless porpoises at various confluences in the Yangtze River suggested that the species tend to prefer areas with low M1, such as flow separation and stagnation zones during the flood season, and more generally the confluence area during the dry season. This preference is likely related to their feeding. The study contributed to a better understanding of the ecological dynamics in the Yangtze River Basin, as well as to the conservation of the endangered finless porpoise
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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