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941.
Tiago M. Barbosa Rui Ramos António J. Silva Daniel A. Marinho 《Journal of sports sciences》2018,36(5):492-498
The aim was to compare the passive drag-gliding underwater by a numerical simulation and an analytical procedure. An Olympic swimmer was scanned by computer tomography and modelled gliding at a 0.75-m depth in the streamlined position. Steady-state computer fluid dynamics (CFD) analyses were performed on Fluent. A set of analytical procedures was selected concurrently. Friction drag (Df), pressure drag (Dpr), total passive drag force (Df+pr) and drag coefficient (CD) were computed between 1.3 and 2.5 m · s?1 by both techniques. Df+pr ranged from 45.44 to 144.06 N with CFD, from 46.03 to 167.06 N with the analytical procedure (differences: from 1.28% to 13.77%). CD ranged between 0.698 and 0.622 by CFD, 0.657 and 0.644 by analytical procedures (differences: 0.40–6.30%). Linear regression models showed a very high association for Df+pr plotted in absolute values (R2 = 0.98) and after log–log transformation (R2 = 0.99). The CD also obtained a very high adjustment for both absolute (R2 = 0.97) and log–log plots (R2 = 0.97). The bias for the Df+pr was 8.37 N and 0.076 N after logarithmic transformation. Df represented between 15.97% and 18.82% of the Df+pr by the CFD, 14.66% and 16.21% by the analytical procedures. Therefore, despite the bias, analytical procedures offer a feasible way of gathering insight on one’s hydrodynamics characteristics. 相似文献
942.
943.
944.
Chris Mawhinney Helen Jones David A. Low Daniel J. Green Glyn Howatson Warren Gregson 《European Journal of Sport Science》2017,17(5):519-529
This study determined the influence of cold (8°C) and cool (22°C) water immersion on lower limb and cutaneous blood flow following resistance exercise. Twelve males completed 4 sets of 10-repetition maximum squat exercise and were then immersed, semi-reclined, into 8°C or 22°C water for 10-min, or rested in a seated position (control) in a randomized order on different days. Rectal and thigh skin temperature, muscle temperature, thigh and calf skin blood flow and superficial femoral artery blood flow were measured before and after immersion. Indices of vascular conductance were calculated (flux and blood flow/mean arterial pressure). The colder water reduced thigh skin temperature and deep muscle temperature to the greatest extent (P?<?.001). Reductions in rectal temperature were similar (0.2–0.4°C) in all three trials (P?=?.69). Femoral artery conductance was similar after immersion in both cooling conditions, with both conditions significantly lower (55%) than the control post-immersion (P?<?.01). Similarly, there was greater thigh and calf cutaneous vasoconstriction (40–50%) after immersion in both cooling conditions, relative to the control (P?<?.01), with no difference between cooling conditions. These findings suggest that cold and cool water similarly reduce femoral artery and cutaneous blood flow responses but not muscle temperature following resistance exercise. 相似文献
945.
946.
Are you ready to teach young children in the 21st century? 总被引:1,自引:0,他引:1
Daniel D. Shade 《Early Childhood Education Journal》1996,24(1):43-44
947.
Postural Sway of Human Infants while Standing in Light and Dark 总被引:3,自引:0,他引:3
Postural sway was measured in 12-14-month-old human infants and in adults while they were standing in the light and dark. Spectral density analyses conducted on all frequencies, at specific frequencies, and for individual subjects showed that infants generally did not sway significantly more in the dark than in the light, whereas adults did. For example, infants' dark/light sway proportions were 1.12 and 1.21 for the anterior-posterior and lateral dimensions, respectively, compared to adult values of 2.23 and 3.43 for one-footed stance, and 1.43 and 2.13 for two-footed stance. A statistical power analysis indicated that if the dark/light proportions for infants had been comparable to those for adults, significant differences could have been detected. These findings indicate that the early regulation of standing posture does not depend on the continuous availability of visual information. 相似文献
948.
949.
The Place of Time in Cognition 总被引:1,自引:0,他引:1
950.
Daniel Callison 《Library & information science research》1997,19(4):347-357
Over the past decade, there has been an increase in the application of the case study method to investigate the process used by students in secondary school and undergraduate academic settings to locate and use information through the library. The case study method has, in most recent years compared to investigations of 20 to 30 years ago, become established as the primary research technique used to document student thought processes in topic focus and in source selection. Direct observation and interviewing successful library users, two tools common to the case study method, may also lead to examination of student selection and critical use of evidence for research projects as students move beyond the traditional library collection. These tools have also proven to be useful as researchers in recent studies are more interested in an analysis of student use of information as evidence rather than conducting studies which only document student location and citation of resources. Selected studies which illustrate this evolution are drawn from the dissertations and field studies related to secondary school and undergraduate bibliographic instruction. 相似文献