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Nonlinear Transformation of Waves over a submerged bar
Get PDFLa crescente necessità di utilizzare e preservare le aree costiere richiede una più approfondita conoscenza delle dinamiche costiere e una migliore capacità di modellare questi processi.
Nello studio della propagazione delle onde verso riva occorre considerare la presenza di eventuali strutture di difesa della costa, come le scogliere emerse e sommerse, che modificano fortemente il campo di moto.
Questa tesi ha l’obiettivo di approfondire la conoscenza dei meccanismi fisici di interazione non lineare tra onde e strutture costiere. A tal fine sono stati condotti esperimenti di laboratorio per studiare la trasformazione sia di onde monocromatiche che di onde random nella propagazione su un ostacolo sommerso.
Le registrazioni della superficie libera sono state elaborate mediante analisi spettrali e bispettrali ed è stata valutata l'influenza di diversi parametri sulle interazioni non lineari delle onde, in particolare gli effetti del periodo ondoso e del frangimento.
L'analisi bispettrale è stata utilizzata per esaminare la variazione spaziale dell’intensità degli accoppiamenti non lineari tra componenti armoniche nel campo d'onda che si propaga sopra e oltre la struttura. Dietro l’opera è stato osservato un comportamento diverso per onde random e monocromatiche. Per le onde random il campo d'onda può ancora essere descritto come sovrapposizione di onde statisticamente indipendenti, senza memoria degli accoppiamenti di fase che esistevano sulla struttura. Le componenti armoniche delle onde monocromatiche continuano invece ad interagire nell'area protetta ed i parametri di asimmetria variano in modo significativo a causa delle differenze di fase variabili tra le onde componenti.
L'evoluzione spettrale delle onde dietro ostacoli sommersi influisce anche sulla risalita ondosa in corrispondenza della spiaggia. Una seconda campagna sperimentale è stata condotta per valutare il run-up su una pendenza impermeabile 1:20 in presenza della struttura sommersa. Il run-up osservato si correla meglio alle caratteristiche dell'onda incidente per le onde monocromatiche regolari e alle caratteristiche degli spettri trasmessi per le onde irregolari. Infatti, per le onde random le interazioni non lineari indotte dalla barra sommersa generano anche onde lunghe che influenzano la componente infragravitativa dello swash. Questo non accade per le onde monocromatiche regolari, dove la prima armonica rimane la principale forzante del run-up.The growing demand to both utilise and preserve our coastal zones causes the need to better understand the coastal dynamics and to improve the capability to model these processes.
In the study of wave propagation towards the shore, it is necessary to take into account the presence of coastal structures, such as submerged and emerged breakwaters , that strongly modify the wave field.
The objective of this thesis is to increase the knowledge and the physical insight on the mechanisms of non-linear interaction between waves and coastal structures.
Laboratory experiments have been carried out to study the transformations of both monochromatic and random waves during the propagation over a submerged obstacle.
The free surface measurements have been elaborated by means of spectral and bispectral analyses and the influence of different wave parameters on the non-linear wave interactions has been evaluated, in particular the effects of the wave period and the wave breaking.
The bispectral analysis is used to examine the spatial variation in intensity of the non-linear couplings between harmonic components in a wave field propagating over and beyond the bar. In the protected area, a different behaviour for random and monochromatic waves is observed. For random waves the bound harmonics are released and the wave field can still be described as a superposition of statistically independent waves, without memory of the phase locks which existed over the bar. Unlike irregular waves, the harmonic components of monochromatic waves continue to interact and the asymmetry parameters vary significantly as a result of the varying phase lags between the freely propagating component waves.
The evolution of the wave spectrum behind submerged obstacles also affects the run-up on the beach. A second experimental campaign has been carried out to evaluate the wave run-up over a 1:20 impermeable slope in presence of the submerged bar. The observed run-up is better correlated to the incident wave characteristics for regular monochromatic waves and to the characteristics of the transmitted spectra for random waves. In fact, for random waves the non-linear interactions induced by the submerged bar also generate long waves that affect the infragravity band swash. This does not happen for regular monochromatic waves, where the first harmonic remains the main forcing of the run-up
Ricostruzione dello spettro ondoso trasmesso dietro un ostacolo sommerso
Get PDFASPETTI CHIAVE • • • Studio dell’interazione onda-struttura sommersa; Ricostruzione dello spettro trasmesso dietro strutture sommerse al variare delle condizioni ondose; Effetto dell’innalzamento del livello marino su strutture sommerse
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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