1,720,967 research outputs found
Livestock vulnerability to flooding
Full text linkThis paper investigates the vulnerability of livestock to flooding. A conceptual model is developed to evaluate the toppling and sliding instability of farm animals exposed to floodwaters. Numerical simulations are also employed to assess the drag, lift and contraction coefficients for some animals among the most commonly farmed. Using the results of the above model together with the few information available in literature, the vulnerability functions for these farm animals exposed to floodwaters are proposed. This is expected to improve flood damage assessment in the agricultural sector, while also enhancing flood risk evaluation and communication to farmers
An efficient physics-based modeling strategy for pluvial floods in urban areas with a subgrid scheme for the stormwater drainage network
Full text linkThis study presents an efficient physics-based modeling strategy for simulating urban pluvial floods, which uses a subgrid approach to account for the contribution of (part of) underground drainage pipes. Coupled with a two-dimensional (2D) hydrodynamic model solving the porous version of the shallow water equations for the free-surface flow, the subgrid formulation allows running rain-on-grid (RoG) simulations while avoiding the time-consuming inclusion of the many small-scale components forming the stormwater network, such as one-dimensional (1D) pipes and storm drains. The proposed model accounts for the anisotropic additional conveyance provided by the stormwater drainage networks, assuming that the water level represents both the local free-surface elevation and the piezometric head for flow in pipes. Model parameters such as pipe direction, diameter, roughness, and spacing, can be derived from aerial images and limited surveys, thus reducing the data requirement and allowing for an easier model implementation than with classical dual-drainage models. Different applicative tests demonstrate that the use of the subgrid model ensures reasonable accuracy with low modelling effort and computational cost. The proposed approach offers an efficient and practical solution for pluvial flood assessment, particularly in data-limited and/or large-scale urban areas, providing support for flood management and mitigation strategies
Flow under vertical sluice gates: Flow stability at large gate opening and disambiguation of partial dam-break multiple solutions
No full textThe present paper deals with two open issues concerning the free orifice flow under vertical sluice gates, namely, the flow stability at large gate openings and the disambiguation of multiple solutions in the case of partial dam-break. The study of these problems, which are mutually connected, is based on ad hoc laboratory experiments and numerical simulations with a computational fluid dynamics model tracking the free surface with the two-phase volume of fluid method. A series of quasi-steady states is used to assess the threshold of relative gate openings that determines the passage from orifice flow to non-interacting flow; in addition, a set of dam-break experiments with partial gate opening (i.e., lower than the initial upstream water level) is performed to find reliable criteria to disambiguate multiple exact solutions supplied by the one-dimensional shallow water theory. It is found that the dependence of contraction and discharge coefficients on the relative gate opening has a dramatic impact on the stability of orifice flow at large gate openings
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
Fully Developed Open Channel Flow Over Clusters of Freshwater Mussels Partially Buried in a Gravel Bed
Full text linkThe present study uses results of eddy‐resolving numerical simulations to investigate the open channel flow over large clusters of freshwater mussels (Unio elongatulus) partially buried in a rough, gravel bed. The density of the mussels forming the array varies from 26 to 500 mussels/m2. The flow structure is analyzed at large distances from the leading edge of the mussel bed, where the flow can be considered fully developed. The effects of changing the mussel bed density, the filtering discharge, the burial level and the roughness of the bed surface in which mussels are burrowed, are investigated in terms of flow field, turbulent structures, drag forces, and bed shear stresses. It is found that strong interactions occur between energetic eddies generated by the larger gravels on the exposed bed surface and by the mussel shells. Simulations results show that for a burial depth close to 50% and a ratio between the average gravel size and the mussel protruding height of 0.13, the shell induced turbulence becomes dominant for mussel bed densities around 50 mussels/m2. The influence of the bed roughness becomes less relevant with increasing mussel density, as the generation of energetic eddies is mostly controlled by mussel‐to‐mussel interactions. For fixed bed roughness, burial level and filtering velocity, the mean streamwise drag force and the associated drag coefficient for the exposed part of each mussel decrease with increasing mussel density, even if strong variations are observed for individual mussels. For constant mussel bed density and burial level, the mean streamwise drag force and the mean drag coefficient decrease slightly with increasing bed roughness. Increasing the burial level decreases not only the drag forces but also the drag coefficients because of the more streamlined shape of the top of the mussels. Strong active filtering acts toward decreasing the mean streamwise force and the mean drag coefficient. The spanwise drag forces contribute significantly to the total drag force, especially for high mussel bed densities. Based on smooth bed calculations, bed‐averaged shear stresses are reduced in highly dense clusters
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
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