1,721,228 research outputs found
Scour below the toe of breakwaters: Investigation of scour formation through a geometrically open filter configuration located at the toe of a rubble mound breakwater lying upon sand
Full text linkScour formation at the toe of a rubble mound breakwater can lead to abrupt failure. Nowadays, counteraction of scour via geometrically closed filter rules, geotextiles or combinations is the common practice. Alternatively, in specific cases the use of geometrically open filters can save significant amount of time and decrease constructional costs. As a primary step towards this direction, the prediction of scour formation through a geometrically open filter can provide important information. Nevertheless, at this moment the knowledge upon this issue is insufficient and limited. A variety of recommendations occurs in literature, separately for toe design/scour protection and for the application of open filter criteria; however none of the studies treats these subjects combined. Therefore the objective of the present thesis is to get insight into scour formation and development through a breakwater toe lying upon sand and designed as a geometrically open filter. Thereby the research aims in drawing the link between scour characteristics with wave loading and filter configuration properties. In order to accomplish the research objective 2D physical model tests were conducted in the 25m long, 1m deep and 0.6m wide wave flume of DMC, installed in the company’s laboratory. In total, 23 tests were executed with irregular waves (Jonswap spectrum) and by varying wave loading and filter configuration properties. In particular, 5 different filter/base layer combinations were examined and 3 different wave conditions were used to investigate the effects of relative grain diameter, relative filter thickness, grading of filter layer, base layer stability Number and storm duration. Quantification of damage magnitude was accomplished via laser profile measurements of filter and base layer prior and after the execution of each test. Furthermore, wave particle velocity climate was determined via the use of an Electromagnetic Flow Meter (EMS) placed at the center of the toe. Finally, temporal evolution scour was captured through the side glass and was examined by digitizing and analyzing snap-shots from predefined time steps. Test results and observations have revealed the highly spatial character of scour formation. Nevertheless, tests with identical boundary conditions showed a surprising convergence in averaged maximum scour depth magnitude. In addition, in the majority of tests an S-curve erosion/deposition pattern was shaped while erosion started immediately at the downstream side of the box threatening breakwater stability. Equilibrium maximum scour depth was reached for less than half the data set; thus erosion process was still in progress. Based on this, two approaches were developed to investigate temporal evolution of scour. Furthermore, dimensional analysis and literature review have revealed the most important parameters that have significant effect in scour formation; their combination has led to the formation of a prediction tool. However, combination of the results from tests with different base materials would not be possible without the introduction of the base material stability Number (critical Shields’ Number). The derived tool is an empirical expression with limited physical background and range of validity. Additionally, it overestimates maximum scour depth due to a serious model effect; the different buoyancy between filter and base layer that was causing initial damage and damage exaggeration. Nevertheless, it is capable of delineating the relative contribution of each parameter in scour depth formation. For an overall view of scour formation, further research will be needed to provide a more accurate quantification of the interrelation between parameters that play a role in scour formation and development, and to implement the effect of missing parameters. Consequently the use of the derived expression as a scour prediction tool in real life is not yet recommended.Hydraulic EngineeringCivil Engineering and Geoscience
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
Damage on rock slopes under wave attack
Full text linkThe aim of this study is the particularisation of the accuracy margins for the determination of the damage level in the experimental plan proposed by Remon Kik at his thesis for the study of Notional Permeability of breakwaters “The experimental research of the permeability factor P”.
The evaluation of the proposed technique took place by means of comparisons between different test cases in order to specify the existence of similarities in the statistical behaviour of original tests and their repetitions. Therefore, statistical tests are used to examine the behaviour of the individual tests not only individually, but also in combination with the rest of the test components
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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