1,721,012 research outputs found
Trasporto solido all'interno di un gruppo di strutture circolari porose: il caso del parco eolico “Mar de Trafalgar”
No full textIl progetto di un parco eolico integrato con impianti per l’itticoltura a Sud Ovest del Golfo di Cadice ha richiesto di effettuare un’analisi dei processi di erosione e deposito dei sedimenti che si realizzano intorno ad una singolo aerogeneratore e all’interno dell’intero parco. Nel presente contributo viene presentato un semplice modello di propagazione del moto ondoso basato su una teoria lineare, in grado di fornire valutazioni sui processi morfodinamici che hanno luogo intorno
alle strutture circolari progettate. A causa della particolare configurazione strutturale dell’insieme pilone dell’aerogeneratore e gabbia di itticoltura, è stato necessario realizzare una modellazione del flusso attraverso mezzi porosi per poter descrivere gli effetti di diffrazione e sfasamento del moto ondoso causati dalla struttura integrata. La valutazione del trasporto potenziale di sedimenti è stata realizzata tramite l’utilizzo di una formula empirica per il trasporto solido al fondo. In questo modo è stato possibile valutare le tendenze erosive che si realizzano intorno a una singola struttura e all’interno dell’intero parco, osservando come, incrementando la resistenza al moto dovuta alla reti delle gabbie, si abbia un aumento dei fenomeni di riflessione e diffrazione. All’aumentare di questi effetti è possibile riscontrare un aumento dei fenomeni di trasporto solido e la formazione di forme di fondo ritmiche
Sediment transport patterns at Trafalgar Offshore Windfarm
No full textA simple analytical model of wave propagation has been developed in order to study the potential sediment transport patterns due to the action of currents and waves in the neighborhood of cylindrical structures as well inside a group of these structures. The attention is focused on the study of Trafalgar offshore windfarm, a case in which it has been necessary to analyze the flow trough porous structures in order to model fish growing-cages planned to be installed at each aerogenerator structure. The results are obtained by averaging over one period of wave in order to evaluate the net potential sediment transport. The analysis of the results reveals how the processes of wave diffraction and reflection give rise to periodic patterns of sediment transport around and between the structures
Sediment transport patterns in the neighbourhood of cylindrical porous structures: The "mar de trafalgar" offshore wind farm
No full textA simple analytical model of wave propagation has been developed in order to study the potential sediment transport patterns due to the action of currents and waves in the neighbourhood of cylindrical structures. The attention is focused in particular on the study of the Trafalgar offshore wind farm, a case in which it has been necessary to analyze the flow trough porous structures in order to model fish growing-cages planned to be installed at each aerogenerator structure. The results are obtained by averaging over one period of wave in order to calculate the net potential sediment transport around a cylindrical impermeable structures surrounded by a porous ring. The analysis of the results reveals how the characteristics of the porous media (friction and porosity) have a strong influence in triggering the processes of wave diffraction and reflection, responsible of the enhancement of strong erosion/deposition processes around the aerogenerator foundation.A simple analytical model of wave propagation has been developed in order to study the potential sediment transport patterns due to the action of currents and waves in the neighbourhood of cylindrical structures. The attention is focused in particular on the study of the Trafalgar offshore wind farm, a case in which it has been necessary to analyze the flow trough porous structures in order to model fish growing-cages planned to be installed at each aerogenerator structure. The results are obtained by averaging over one period of wave in order to calculate the net potential sediment transport around a cylindrical impermeable structures surrounded by a porous ring. The analysis of the results reveals how the characteristics of the porous media (friction and porosity) have a strong influence in triggering the processes of wave diffraction and reflection, responsible of the enhancement of strong erosion/deposition processes around the aerogenerator foundation. © 2007 World Scientific Publishing Co. Pte. Ltd
3D flow measurements in regular breaking waves past a fixed submerged bar on an impermeable plane slope
Full text linkThe velocity fields induced by regular breaking waves past a fixed bar on a 1:10 rigid plane slope were measured and analysed using a volumetric particle-tracking velocimetry system. Under specific conditions, the wave-mophological features interaction steepens the waves which eventually breaks. The geometry of the boundaries of the present experiments is common in natural environments, where reefs, sand and gravel bars, and submerged coastal structures, interact with the incoming wave field 'affecting' the transport budget of substances (sediment, nutrients and pollutants), with relevant consequences on the water quality. The aims of the present work are the analysis of the flow field in the breaker, the quantification of the terms in the equations usually adopted for modelling the flow and the turbulence. Two sets of attacking monochromatic wave trains with different periods and heights were used to generate a dataset of instantaneous velocity, which was further analysed to extract turbulence. The measurement volume extended
from the wave crest to a portion of the domain below the wave trough. The balance of linear momentum for the average field and the balance of turbulence, were scrutinised and included all the terms in a 3D approach. The analysed data and results are original and novel because they include all the contributions derived from the 3D structure of a real flow field, and constitute a huge data set for calibration of numerical codes
Storm characterization and simulation for damage evolution models of maritime structures
No full textThis paper presents a new approach to statistically characterize and simulate the wave climate under storm conditions. The methodology includes the joint selection of the parameters that identify storm events (significant wave height threshold, minimum storm duration and minimum interarrival time between consecutive storms) by means of hypothesis testing on the distribution functions of the number of storm events and the elapsing time between storms, providing an improved characterization of the parameters that define storm events. The main wave variables and their temporal dependence are characterized by non-stationary mixture distribution functions and a vector autoregressive model. This allows to adequately reproduce the random temporal evolution of storm events, crucial for the study of damage progression in maritime structures without the use of predefined geometries. The long-term time series of storm events and calm periods is obtained using copula functions which analyze the joint dependence of storm duration and interarrival time for separate climate intervals. The model is applied to hindcast data at a location of the Mediterranean sea close to the Granada coast in Spain to show its ability to reproduce wave storm conditions accounting for the time variability of the storminess. An example of application, using a large number of simulations and a damage progression model in a maritime structure, is presented
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
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