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排序方式: 共有493条查询结果,搜索用时 15 毫秒
471.
George B. Grant 《Journal of The Franklin Institute》1889,128(3):208-209
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The aim of this study was to examine heart rate, blood lactate concentration and estimated energy expenditure during a competitive rugby league match. Seventeen well-trained rugby league players (age, 23.9 +/- 4.1 years; VO2max, 57.9 +/- 3.6 ml x kg(-1) x min(-1); height, 1.82 +/- 0.06 m; body mass, 90.2 +/- 9.6 kg; mean +/- s) participated in the study. Heart rate was recorded continuously throughout the match using Polar Vantage NV recordable heart rate monitors. Blood lactate samples (n = 102) were taken before the match, after the warm-up, at random stoppages in play, at half time and immediately after the match. Estimated energy expenditure during the match was calculated from the heart rate-VO2 relationship determined in laboratory tests. The mean team heart rate (n = 15) was not significantly different between halves (167 +/- 9 vs 165 +/- 11 beats x min(-1)). Mean match intensity was 81.1 +/- 5.8% VO2max. Mean match blood lactate concentration was 7.2 +/- 2.5 mmol x l(-1), with concentrations for the first half (8.4 +/- 1.8 mmol x l(-1)) being significantly higher than those for the second half (5.9 +/- 2.5 mmol x l(-1)) (P<0.05). Energy expenditure was approximately 7.9 MJ. These results demonstrate that semi-professional rugby league is a highly aerobic game with a considerable anaerobic component requiring high lactate tolerance. Training programmes should reflect these demands placed on players during competitive match-play. 相似文献
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Grant?TrewarthaEmail author Maurice?R.?YeadonEmail author Jon?P.?Knight 《Sports Engineering》2003,6(3):139-148
This paper introduces the first stage of a new model-based approach to three-dimensional (3D) human movement tracking. A ‘generate-and-test’
matching procedure was adopted by matching rendered images of a 3D computer graphics model of the human body to target images
of rigid body motion. The set of pixels to be compared were just those corresponding to the model of the body in the rendered
images. The matching criterion to optimize model position and orientation was based on the minimisation of the RGB (red-green-blue)
colour difference between generated model images and associated target images. The method was able to track synthetic image
sequences of a half twisting somersault accurately with root-mean-square (rms) errors of less than 5 mm and 0.3∘ for position
and orientation estimates respectively. The suitability of the proposed approach for rigid body motion tracking was supported
by additional tracking experiments on video image sequences of ‘wooden cross’ trajectories. Comparisons of tracked estimates
against manual digitizing estimates returned relatively small rms difference values on both side somersault and twisting somersault
movements. The proposed approach has the potential to track video images of a human torso using a rigid body model and hence
to track articulated movements by successively adding segments to the model in a hierarchical manner. 相似文献
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Grant Harman 《Higher Education》1994,27(3):313-339
Student selection and admission for higher education in the Asian region are matters of concern at a time when there is rapid growth in enrolments and mounting pressure for changes, and when public funds are unable to match demands for expansion. This paper provides a broad review of policies and practices in developing and newly industrialised countries of the Asian region, paying particular attention to access, selection, the admission process, equity and links to the labour market. It attempts an evaluation and provides suggestions for policymakers. 相似文献