1,722,603 research outputs found
Identifying race time benefits of best practice in freestyle swimming using simulation
No full textIn the preparation of a swimmer for a race, it is not currently possible to determine the race time impacts of changes to equipment or technique. This study addresses this problem, by modelling the resistive and propulsive forces experienced by a swimmer, throughout the various phases of a race, to predict race time.Swimming resistance is quantified for surface and underwater swimming, across a population of swimmers, using computational methods and bespoke measurement equipment. Due to the low repeatability, when measuring swimming resistance, statistical methods are utilised to quantify confidence in the measured data. For five repeat tests a 1.8% difference in swimming resistance can be resolved with 95% confidence. Arm propulsion is modelled, treating the arm as a single element moving through the water, producing drag. Leg propulsion is modelled using Large Amplitude Elongated Body Theory originally derived by Lighthill to predict the propulsion generated by fish. This enables freestyle flutter kick, when swimming on the surface, and underwater undulatory swimming, after the start and turn, to be modelled. Input motion for both arm and leg propulsion is determined from manual digitisation of video data, providing the body kinematics of a kick and the time accurate arm speed. Accurate swimming speed for a given stroke rate is achieved by comparing the simulated output with experimental data and scaling the arm and leg parameters. Using a race phase algorithm, the swimming speed for each phase of a swimming race is simulated.To simulate fatigue, metabolic energy sources are considered. Both maximum power and energy capacity, for aerobic and anaerobic energy sources, are determined from literature. Using PI control of stroke rate, swimming fatigue is simulated by ensuring the propulsive power does not exceed the total available power from the energy model. Therefore, as a swimmer progresses through a race, the available power depletes, causing stroke rate and hence swimming speed to decay.Combining these models, enables simulation of swimming speed and fatigue throughout a race, from which race time is predicted. The race time impact of changes to swimming resistance and propulsion are investigated. Resistance and propulsion changes from equipment, drafting and technique are quantified experimentally. A 9.5% reduction in swimming resistance, affecting the whole race or underwater phases only, has been found to improve a 100 m race time by 2.75s or 0.99s respectively
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
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
Arbitrage, contract design, and market structure in Bitcoin futures markets
No full textPerpetual futures, first proposed by Shiller (1993), have only seen wide use in cryptocurrency markets. We examine the contract design and market microstructure differences for the behavior of Bitcoin quarterly and perpetual futures prices and assess the implications for market participants and policymakers. We find perpetual futures exhibit multiple “u-shaped” curves, seasonal effects, and opening effects despite lacking opening and closing hours. There is suggestive evidence of spillover effects between perpetual and quarterly futures contracts. We find quarterly futures offer cash-and-carry arbitrage opportunities, but similar to Hattori and Ishida (2021) these opportunities primarily exist during market dislocations
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
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