1,720,962 research outputs found
Air Bubble Entrainment by Breaking Waves and Associated Energy Dissipation
Get PDFA simple mathematical model (air bubble model) that describes energy dissipation due to air bubble entrainment is proposed and applied to a series of laboratory experiments for plunging jet flows (steady) and surf zone waves (unsteady). This leads to a formulation wherein the rise velocity of bubbles is included. For the unsteady case, i.e. air entrainment by wave breaking, some parameters of the model have been estimated from the experiments and expressed in terms of local wave height and distance. Results obtained through the air bubble model are summarized in the following. Experiments in vertical circular plunging jets (steady) were performed for both in freshwater and seawater, which highlighted the distribution of void fraction, that follows closely analytical solutions derived by Chanson (1997). In addition, various properties of void fraction field were emphasized. Three scale models were used with freshwater for identical Froude numbers in the experiments, which highlighted significant scale effects when Weber number is less than 1000. Similar experiments were also performed with freshwater and seawater and the results showed lesser air entrainment in seawater plunging jets. The pseudo-bubble chord sizes obtained from the experimental data were in the range from less than 0.5 mm to more than 1.0 mm. The rate of energy dissipation due to entrained air was investigated by applying the air bubble model for three typical phenomena. The results demonstrated that the ratios of energy dissipation due to air bubble entrainment with respect to total energy loss were 25%, 1.4% and (2-4)% for hydraulic jump, 2-D vertical plunging jet and vertical circular jet, respectively. Experiments on unsteady air bubble entrainment by wave breaking were conducted in a wave channel. Maps of the evolution of the void fraction distribution in surf zone generated by various sizes breaking waves were presented. A significant fraction of the potential energy of entrained air was measured from the void fraction distributions provided by breaking waves. Measurements showed high void fraction up to 19% in plunging breakers at still water surface whereas 16% in spilling breakers. The ratio of energy dissipation due to entrained air to total energy loss was found (18-22)% and (17-19)% for spilling and plunging breaker, respectively. The characteristics of time averaged wave parameters (e.g. potential energy, kinetic energy, energy flux, radiation stress) for regular waves were discussed taking into account the air bubble effects. Analytical solutions were sought and explicit expressions were obtained for wave parameters under sinusoidal waves. Effects of the air entrainment on density, pressure and velocity fields were also discussed in detail. The conservation equations for energy and momentum were solved numerically using finite difference methods. Boundary conditions were used at the breaking point. Scale effects were discussed based on laboratory air entrainment in 2-D wave flume, which was believed to occur in small size models. The data were in good agreement with the basic assumption for vertical distribution of void fraction both in spilling and plunging breakers. The results of the air bubble model were compared with experimental data and found to give good agreement between them for the wave height and wave setup. Water level rise by entrained air was determined and found significant effects on surf zone hydrodynamics. In addition, wave run-up was measured and discussed
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
A Mathematical Model of Avian Influenza for Poultry Farm and its Stability Analysis
Get PDFThis paper aims to estimate the basic reproduction number for Avian Influenza outbreak in local and global poultry industries. In this concern, we apply the SEIAVR compartmental model which is developed based on the well-known SEIR model. The SEIAVR model provides the mathematical formulations of the basic reproduction number, final size relationship and a relationship between these two phenomena. The developed model Equations are solved numerically with the help of Range-Kutta method and the values of initial parameters are taken from the several literatures and reports. The calculated result of basic reproduction number shows that it is locally and globally stable if it is less than and greater than one at disease free equilibrium and at endemic equilibrium, respectively. Furthermore, we have compared among the calculated susceptive, expose, infective, removal, virus and asymptotic compartments where infection rate and expose period are observed very sensitive compared to other parameters. In addition, the model result of infective is compared with the field data and other’s model where the present model shows good performance against the field data
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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