1,720,980 research outputs found
Site Response in Liquefiable Layered Deposits Considering Spatial Variability in Hydraulic Conductivity
No full textPrevious studies have revealed that evaluation of the liquefaction hazard using mean estimates of soil properties may not adequately capture the response of intrinsically inhomogeneous granular soils, their interactions, and the subsequent inter-layer flow patterns that control the generation and redistribution of excess pore pressure during and after cyclic loading. Hence, they cannot reliably predict the liquefaction hazard and its consequences on site performance in terms of accelerations and deformations. In a parametric numerical study that was initially validated against centrifuge experiments, solid-fluid, fully-coupled, nonlinear dynamic effective stress analyses were performed to evaluate the effects of spatial variability of hydraulic conductivity (k) on seismic site response in layered sand deposits. The pressure-dependent, multiyield-surface, nonlinear, plasticity-based soil constitutive model (PDMY02) implemented in OpenSees was used to simulate the behavior of saturated sand. Analyses were conducted on a high performance computer using the parallel version of OpenSees framework. The Local Average Subdivision method was used to generate and map a stochastic k field over the finite element mesh. The base rock was simulated as an elastic half-space. The influence of k variability on the liquefaction hazard and consequences, including the timing of liquefaction, the resulting accelerations, and key intensity measures (IMs) were evaluated. The results indicate notable differences between the deterministic and median of the stochastic approaches in terms of key surface ground motion IMs as well as the extent and timing of excess pore pressure generation within the liquefiable layer
The effect of clay water content in the Jet Erosion Test
No full textThe understanding of the onset of breaching induced by surface erosion is fundamental to enable definition of the level of protection afforded by embankments and provision of standards for the design of new structures and the upgrading of existing ones. Compacted embankment materials are generally partially saturated due to seasonal variation in the water content. At the onset of the overflow process embankments undergo to a wetting process due to the changes at the outer surface boundary conditions (i.e. overflow). Erosion behaviour is known to be a counterbalance between gravity forces and shear erosion forces. However, as the particle size decreases (i.e. clayey soils), gravitational forces become negligible and electrochemical interaction between particles play a dominant role. Clay microstructure (e.g. particle configuration and inter-particle forces) changes with the hydro-mechanical stresses history. Thus, it is necessary to consider the microstructural changes in particle configuration to understand the influence of microstructure on the macroscopic behaviour of clay during erosion. Upon wetting, clay have a swelling/collapse behaviour. This research presents experimental results on erosion of clay samples compacted at the same initial dry density but with different compaction water content. The influence of different wetting times on erosion is also investigated. We show that for a given as-compacted water content, the longer the wetting stage, and hence the higher the sample water content, the more erodible the samples. Additionally, for samples compacted at the same dry density, the ones compacted on the dry side of optimum are more erodible than samples compacted at the optimum water content, despite the lower water content at formation. We hypothesise that this may be due to the formation of a different initial microstructure in sample on the dry side of optimum (i.e. bi-modal pore size distribution). Our results contribute to the fundamental understanding of time-dependent mechanisms that influence erosion of clay embankments during overflow and, hence, to embankment failure. In addition, these tests show how basic concepts of unsaturated soil mechanics can serve as a guide to ‘design’ the compaction conditions of embankment material
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
Suction as an untapped natural soil reinforcement to reduce embodied carbon in geotechnical structures : the case study of flood embankments in Hamburg area
Full text linkThe commitment to cut CO2 emissions is now becoming a matter of legal obligations in several countries worldwide and the construction industry, one of the main sectors contributing to carbon emissions, is required to develop new approaches for carbon-efficient design. A study was undertaken to examine whether the inclusion of negative pore-water pressures (or 'suction') in the design of a flood embankment could reduce the embodied carbon associate with the construction of a new embankment or the retrofitting of an existing one. The case considered here are the embankments of the tidal Elbe area in Germany that require to be raised because of the new projection of extreme river levels due to climate change. Simple uncoupled water flow and stability analyses were considered to examine the performance of given embankment geometry. The purpose of the study is to examine whether incorporating suction into the design could allow for steeper landside slopes of the flood embankment. This would allow raising the embankment by saving considerable material and, hence, reducing the embodied carbon. At the same time, this would reduce the footprint of the raised embankment, which is a design requirement when flood embankments are embedded in the built environment as it happens in Hamburg
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
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