1,720,963 research outputs found
Cross-sectional stability of double inlet systems
No full textBarrier coasts and their associated tidal inlet systems are a common feature in many parts of the world. They constitute dynamic environments that are in a continuous stage of adapting to the prevailing tide and wave conditions. Commonly, these coastal areas are densely populated and (partly) as a result there often exists a strong conflict of interests between issues related to coastal safety, economic activities and ecology. To manage these different interests, it is important to gain more understanding of the long-term morphological evolution of tidal inlet systems and their adaptation to natural changes and human intervention. In this thesis the focus is on double inlet systems, where two tidal inlets connect a back-barrier basin to an ocean or a coastal sea. To investigate the morphological evolution of double inlet systems and their adaptation to internal or external change, the equilibrium configuration and stability properties of the cross-sectional areas of the two tidal inlets are studied in detail. To that extent, a widely used empirical relationship for cross-sectional inlet stability is combined with (i) a lumped-parameter (L-P) model (Chapters 2 and 3) and (ii) a two-dimensional, depth-averaged hydrodynamic (2DH) model for the water motion (Chapter 4). The Marsdiep-Vlie inlet system in the western Dutch Wadden Sea and the Faro-Armona inlet system in the Portuguese Ria Formosa serve as case studies throughout this thesis. With the assumptions of a cross-sectionally averaged, uniform inlet flow velocity and a uniformly fluctuating basin surface elevation, model results of the L-P model show that stable equilibrium configurations where both inlets are open exist. It is necessary, however, to account for the important processes either explicitly, e.g. including a topographic high in the back-barrier basin as observed in the Wadden Sea (Chapter 2), or parametrically, e.g. allowing for inlet entrance/exit losses for relatively short inlets such as in the Ria Formosa (Chapter 3). By solving the depth-averaged, linear shallow water equations on the f-plane with linearised bottom friction, the 2DH model explicitly accounts for spatial variations in surface elevation in the ocean, inlets and basin. Model results show that these spatial variations, induced by e.g. basin bottom friction, radiation damping, and Coriolis effects, are crucial to simulate and explain the long-term evolution of double inlet systems. This approach further allows the identification of a stabilising and destabilising mechanism associated with the persistence or closure of one (or both) of the inlets in a double inlet system and hence with its long-term evolution.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
Equilibrium and stability of a double inlet system
No full textBarrier island coasts are a common feature in many parts of the world. An example is the Wadden coast of The Netherlands, Germany and Denmark. These coasts consist of barrier islands separated by tidal inlets with at the landward side tidal basins.Characteristic for the Wadden Sea is that the tidal basins are not completely separated,but are connected via topographic highs allowing exchange of water between the basins. As a result the tidal inlets that connect the basins to the North Sea will interact. The focus in this thesis is on the effect of this interaction on the cross-sectional equilibrium and stability of tidal inlets that are part of a double inlet system. The knowledge gained in this study will help to develop rational management plans for this kind of system. In determining the equilibrium values and stability of cross-sectional areas of the inlets use is made of flow diagrams. A flow diagram consists of the equilibrium flow curves of each inlet and a flow field showing the adaptation of the inlet cross-sections after the system has been removed from equilibrium. Each intersection of the equilibrium flow curves represents a stable or unstable equilibrium. The equilibrium flow curve for each inlet is the locus of the values of the cross-sectional areas for which the velocity amplitude in the inlet equals the equilibrium velocity i.e. approximately 1 m/s according to ESCOFFIER [1940]. As a start the double inlet system is schematized as a basin connected to the ocean by two channels. The water surface area of the basin is assumed constant and water levels are assumed to fluctuate uniformly. On the seaward side a simple harmonic, semidiurnal tide is used to force the system. Analyzing the double inlet system under these conditions by means of the flow diagrams leads to the conclusion that a stable equilibrium of the two inlets does not exist. Ultimately only one inlet remains open and the other will close. This confirms the earlier conclusions of VAN DE KREEKE [1990] and BORSJE [2003] concerning the cross-sectional stability of multiple inlet systems.Civil Engineering and Geoscience
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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