1,720,962 research outputs found
Physical and numerical modelling of wave transformations in the Venice Lagoon
No full textAim of the study is to assess the capability of a numerical model to reproduce the wave modification when propagating in a very shallow water environment crossed by small canals. This is a typical situation within the Venice Lagoon, and it does appear that the wave transformation due to the cutting canals can be responsible of bank erosion and of other important phenomena (e.g. reflection and set-up/down).
A suitable wave model was therefore applied to the “academic case” of a rectangular trough of finite width, and compared with the results obtained through the laboratory tests, specifically performed in a wave flume. The applied model, SWAN, is an advanced third generation model, specifically developed for shallow waters. The model is based on the wave action balance equation with sources and sinks terms. Being the wave action conserved for a wave propagating in non-homogeneous media, the SWAN model seems to fit the requirements to correctly reproduce the wave evolution over a trough.
Once validated with the laboratory data, the wave model could be applied to the convoluted bathymetry of the lagoon and used to get an estimate of the energy dissipation on the canals’ edges and eventually an estimate of the slopes erosion
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
Tidal Networks: Form and Function
No full textWe review some geomorphological properties of tidal networks and their embedded landforms, aiming at inferring their leading eco-morphodynamic interrelations. Indeed the interplay of vegetation patterns (hence the ecological edge) and surface morphology (including the nested networks cutting through salt marshes and their embedding tidal flats, overall portraying an inevitably complex coevolution) is key to the dynamics of the tidal landscape. Through the extraction of network patterns from topographic or bathymetric fields and aerial imaging, we consider analyses of the resulting morphologies what-ever their age and stability, in particular by looking at the structures that control the landscape-forming hydrodynamics. We also provide a brief but hopefully significant comparative analysis with river networks, to look at similarities and departures in the light of invariance properties over a range of scale, which, of course, bear dynamic implications. Watershed delineation through the identification of suitable ‘divides’, elongations of nested tidal basins, regime (or empirical regime-like) theories, statistics of network lengths, drainage densities facing the patterns of halophytic vegetation (in itself a key morphodynamic factor) and meandering features are considered. Great diversity is observed, rather than common patterns, in the tidal landscape. This diversity is suggested to stem from the pronounced spatial gradients of landscape-forming flow rates and to the imprinting of several crossovers from competing dynamic processes that confuse any tendency towards scale-invariant forms and functions. We claim that this basically differs from the river basin morphology owing to the dominance of invariant fluvial erosion processes over many scales therein
Geomorphological properties of a lagoonal system
No full textAnalyses of the observational morphological structure of a lagoonal landscape are performed
aimed at examining key assumptions on the geomorphological evolution of wetlands, lagoons, estuarine areas
and tidal environments in general. The present note briefly refers about analysis (Feola et al. 2005) regarding
statistical measures, morphodynamic implications of topological or metric properties of the observed landforms.
In order to accurately characterize morphodynamic features of a lagoonal environment with particular attention
to their scale-dependent (or invariant) characters, field surveys and remote sensing are employed.The structure of
landscape-forming shear stresses is calculated in unchanneled portions of the landscape suggesting the viability
of threshold models of incision for the formation of tidal channel networks. Distinctive geomorphic indicators,
suitable for comparative purposes with modelling of the long term evolution of tidal systems, are also pointed
out. Space-distributed analyses of eco-geomorphological properties which strongly suggest the dominance of
sub-vertical processes in the control of the distribution of halophytic vegetation are finally discussed
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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