1,720,954 research outputs found
Mathematical model of high speed planing dynamics and application to aircraft ditching
No full textA nonlinear mathematical model capable of predicting loads and motions of high speed planing craft in the longitudinal plane has been developed. The development of the model is based on the mathematical model presented by Zarnick (1978). Following the principle of 2D strip theory and wedge water entry problem, a high speed planing hull is divided into a number of transverse sections. Sectional forces and motions are evaluated, and then, by integrating along the ship length, total force and moment are obtained which leads to corresponding instantaneous acceleration. By integration using a time marching scheme, velocity and displacement are obtained. The influence of the controlling parameters, such as number of sections and time step, on the accuracy and stability of the simulation in calm water, regular and irregular waves is investigated.The accuracy of the underlying mathematical model is investigated and the deficiencies identified. The optimum model is finally validated against the original model of Zarnick(1978) and the experiments of Fridsma (1969).An extension of the model to be capable of simulating roll motion is proposed and implemented. This extension may be useful when the prediction of high speed planing motions in oblique seas is proposed. The initial validation process has been carried out but subjected to the full validity of application.Moreover, as the original approach of the mathematical model was used in prediction of seaplane landing (Wagner, 1931), an additional aim and objective to the present PhD project is to find a novel technique to predict the loads on fuselage of an aircraft emergently landing (ditching) into the water. Experimental tests related to these simulations are planned and carried out in order to use their results as validation references to the modified mathematical model. The deliverable of the project is an analysis of optimization of the mathematical model capable of predicting loads and motions of high speed planing craft. As well as the implementation of capability of predicting impact loads and initial post-impact motions of aircraft ditching into the water
Development and optimization of mathematical model of high speed planing dynamics
No full textA nonlinear mathematical model capable of prediction load and motions of high speed planing craft in thelongitudinal plane has been developed. The development of the model is based on the mathematical modelpresented by Zarnick (1978). Following the principle of 2D strip theory and wedge water entry problem, a highspeed planing hull is divided into a number of transverse sections. Sectional forces are evaluated, and then,integrating along the ship length, total force and moment are obtained which leads to correspondinginstantaneous acceleration. By integration using a time marching scheme, velocity and displacement areobtained. Solution of the motions of a planing craft based upon strip theory and wedge water impact is wellknown and offers fast computational times useful for simulation and design. However it is necessary tounderstand the balance between rapid computation and accuracy of this approach. Thus, The influence of thecontrolling parameters, such as number of sections and time step, in the accuracy, stability and computationaltimes of the simulation in calm water and regular waves is investigated. The optimum model is finally validatedagainst the original model of Zarnick (1978) and the experiments of Fridsma (1969
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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