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Currently, all elite high jumpers use the Fosbury Flop technique with a curved approach. This suggests that the curved approach presents some clear advantage, although there is no general agreement upon the mechanism or the mechanics. This study aimed to determine the characteristics of the approach curve and to investigate how it contributes to the generation of somersault rotation. A simple theoretical model was used to demonstrate that a tightening approach curve would change the inward lean towards the centre of the curve into outwards lean. Three-dimensional video analysis was used to record the performances of two elite male high jumpers in competition. It was found that in each case the radius of the approach curve and the inward lean angle both decreased towards the end of the approach. The amount of outward lean angular velocity generated was shown to be a major proportion of the required somersault angular velocity for a jump. It was concluded that the main advantage of a curved approach was that it resulted in the generation of somersault velocity providing the curve tightened towards the end of the approach. 相似文献
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Konstantinos Petridis Chrisovalantis Malesios Garyfallos Arabatzis Emmanuel Thanassoulis 《Journal of Informetrics》2013,7(2):505-521
In this paper we attempt to assess the impact of journals in the field of forestry, in terms of bibliometric data, by providing an evaluation of forestry journals based on data envelopment analysis (DEA). In addition, based on the results of the conducted analysis, we provide suggestions for improving the impact of the journals in terms of widely accepted measures of journal citation impact, such as the journal impact factor (IF) and the journal h-index. More specifically, by modifying certain inputs associated with the productivity of forestry journals, we have illustrated how this method could be utilized to raise their efficiency, which in terms of research impact can then be translated into an increase of their bibliometric indices, such as the h-index, IF or eigenfactor score. 相似文献
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《海洋奇缘》(Moana)是美国迪士尼动画公司的第57部动画长片.
故事讲述了主宰风和海的半神毛伊(Maui)偷走了女神特菲提(Te Fiti)之心,导致岩浆魔鬼厄卡(Te Ka)陷入疯狂的状态,南太平洋各小岛也面临着毁灭的威胁.一千多年后,某小岛上的酋长之女莫阿娜(Moana)在父母的呵护下渐渐长大,童年时她曾偶然捡到特菲提之心,亦曾受到大海的召唤,然而父亲却严厉禁止莫阿娜出海,即使小岛正遭受着毁灭的威胁.从奶奶那里,莫阿娜知晓了他们这一族人的历史.于是为了拯救小岛,她毅然出海去寻找被困在某地的毛伊,好让他归还特菲提之心.历经千辛万苦,莫阿娜终于见到了这个传说中高傲自大的半神.然而,毛伊却因为担心特菲提之心会带来霉运而拒绝完成这个使命.最后,在命运的指引下,毛伊不得不随着莫阿娜踏上了波澜壮阔的海洋冒险之旅. 相似文献
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The purpose of this article is to come up with a valid categorization and to examine the performance and properties of a wide range of h-type indices presented recently in the relevant literature. By exploratory factor analysis (EFA) we study the relationship between the h-index, its variants, and some standard bibliometric indicators of 26 physicists compiled from the Science Citation Index in the Web of Science. 相似文献