1,720,959 research outputs found
An overtopping formula for shallow water vertical seawalls by SWASH
Full text linkThere is now wide evidence that phase -resolving numerical models can capture the general physics of the overtopping process even under complex hydrodynamics. Based on this outcome, an extensive parametric study has been carried out with the model SWASH, to develop a design formula that uniformly predicts the overtopping rate at vertical seawalls for both breaking and non -breaking wave conditions. The use of the numerical model has allowed to vary the experimental conditions smoothly, avoiding the typical limitation of laboratory experiments. Furthermore, particular tests have been performed to assess whether, and up to which extent, the mean overtopping discharge is affected by the low frequency components of the incident wave spectrum. The formula relates the overtopping rate to a new water level statistic, which represents the average of the highest one-fourth wave displacements at the toe of the wall; it has initially been derived for planar beaches and then extended to the case of slope varying foreshores. A comparison with an array of 200 laboratory experiments confirms that the new parametrization can reduce the scatter of data compared to the EurOtop equation
Predicting crenulate bay profiles from wave fronts: Numerical experiments and empirical formulae
No full textFor crenulate-shaped bays, the coastal outline assumes a specific shape related to the predominant waves in the area: it generally consists of a tangential zone downcoast and a curved portion upcoast. Many coastal engineers have attempted to derive an expression of the headland bay shapes that emerge when a full equilibrium is reached (stable or dynamic). However, even though models for static equilibrium bays exist, they are merely of an empirical kind, lacking further insight on relationships between incident wave characteristics and beach shape. In addition, it is commonly believed that shoreline profiles tend to follow wave fronts, but this has been never fully verified. In this paper, we investigate a possible correlation between static equilibrium profiles and wave front shapes. Numerical experiments have been performed using the MIKE 21 Boussinesq Wave module, and the generated wave fronts have been compared to the hyperbolic-tangent equilibrium profile. A thoughtful analysis of results revealed that a single-headland equilibrium profile is merely the wave front translated perpendicularly to the wave direction at the headland tip, without any influence of wave period or in wave direction. A new function called the “wave-front-bay-shape equation” has been obtained, and the application and validation of this formula to the case-study bay of the Bagnoli coast (south-west of Italy) is described in the paper
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
Wave overtopping at a vertical seawall by Boussinesq modeling
No full textNumerical models may represent a useful tool to estimate wave overtopping discharge. However, so far there is still little available literature on numerical modeling, especially on Boussinesq modeling. The paper analyses the ability of a BTM, Celeris, to predict wave overtopping at a vertical seawall with shallow foreshore, comparing numerical outcomes with physical results of an experimental campaign carried out at the University of Naples Federico II, Italy. The validation has shown that the model needs to be calibrated to avoid overestimation and obtain a reliable tool. In this paper we opted to calibrate the Manning coefficient, which acts as an additional dissipative term to limit overestimation and achieve accurate assessments
THE EFFECT OF WIND STRESS ON WAVE OVERTOPPING ON VERTICAL SEAWALL
No full textOnshore wind can significantly affect wave overtopping process and increase mean overtopping discharge. Thus, thewind should be an important variable in coastal design process. However, despite many researches have analyzed theinfluence of wind on the overtopping, there is still a lack of exhaustive knowledge about this phenomenon. To furtheranalyze the wind effects, the CFD model FLOW-3D has been used to investigate wave overtopping at vertical seawalls.The single-fluid approach has been adopted, i.e. the presence of wind has been simulated via the wind shear stress onthe sea surface. The main aim of this work is to verify the ability of this simplified numerical modelling to capture themacro-processes involved in the phenomenon of wave overtopping. The presence of wind shear stress has led tophysically consistent results. It confirmed that as the mean overtopping discharge decreases, as the wind effect increases.Furthermore, numerical results have shown that the advection of water droplets behind the structure by the wind is thekey mechanism for the enhancement of wave overtopping. Finally, by gathering numerical results and laboratory datacarried out by Durbridge (2021), a new predictive formula to estimate the wind factor is provide
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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