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1.
Rowlands J Forrester W Coelho L Cardy L Yeadon J 《Health information and libraries journal》2001,18(1):45-53
The paper considers how attributes and skills fundamental to the information profession may be applied to the development and management of Web-based services and resources. It also looks at the need for the acquisition of new skills as part of a continuing professional development programme. The report considers the changing role of the Webmaster and the implications this might have in terms of the role of information professionals. To offer a practical example, from within the healthcare sector, the article goes on to describe the development of BMA Library Online. This is the BMA Library's own suite of Web-based information services and resources for personal members, institutional members and staff. The library's own Web team has been responsible for the development and maintenance of BMA Library Online. To conclude, the paper looks forward to future possibilities for information professionals as Web developers and at how this might be influenced by changes in the Webmaster role. It is crucial that skills and expertise are shared as the roles that go to make up a Webmaster or Webmaster team continue to merge and evolve, and with the possible wider distribution of provision of Web content within organizations. 相似文献
2.
In this study a method for determining elbow extension and elbow abduction for a cricket bowling delivery was developed and assessed for Jenny Gunn who has hypermobility in both elbows and whose bowling action has been repeatedly queried by umpires. Bowling is a dynamic activity which is assessed visually in real time in a cricket match by an umpire. When the legality of a bowler's action is questioned by an umpire a quantitative analysis is undertaken using a marker based motion analysis system. This method of quantifying elbow extension should agree with a visual assessment of when the arm is "straight" and should minimise the effects of marker movement. A set of six markers on the bowling arm were used to calculate elbow angles. Differences of up to 1° for elbow extension and up to 2° for elbow abduction were found when angles calculated from the marker set for static straight arm trials were compared with measurements taken by a chartered sports physiotherapist. In addition comparison of elbow extension angles at ball release calculated from the markers during bowling trials with those measured from high speed video also showed good agreement with mean differences of 0°±2°. 相似文献
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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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M.R. Yeadon 《Journal of sports sciences》2013,31(3):199-208
A simulation model and a rigid body model are used to investigate twisting initiated during the take‐off or contact phase. It is shown that it is possible to produce a full twist solely by building up angular momentum in the arms during the contact phase. This method is only half as effective as building up momentum in the whole body during contact. The introduction of twist into a somersault changes the somersault rate by less than 1%. By timing arm adduction appropriately, it is possible to take advantage of nutation and boost the initial value of the tilt angle and so obtain a greater twist rate. Twist may be stopped by the action of piking, since the motion changes from the twisting mode to the wobbling mode of rigid body motion. Transition to and from these two modes can be used to increase or decrease the tilt angle and twist rate. 相似文献
6.
Biomechanical aspects of playing surfaces 总被引：2，自引：1，他引：1
The purpose of this paper is to discuss some biomechanical aspects of playing surfaces with special focus on (a) surface induced injuries, (b) methodologies used to assess surfaces and (c) findings from various sports. The paper concentrates primarily on questions related to load on the athlete's body. Data from epidemiological studies suggest strongly that the surface is an important factor in the aetiology of injuries. Injury frequencies are reported to be significantly different for different surfaces in several sports. The methodologies used to assess surfaces with respect to load or performance include material tests and tests using experimental subjects. There is only little correlation between the results of these two approaches. Material tests used in many standardized test procedures are not validated which suggests that one should exercise restraint in the interpretation of these results. Point elastic surfaces are widely studied while area elastic surfaces have received little attention to date. Questions of energy losses on sport surfaces have rarely been studied scientifically. 相似文献
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ABSTRACT Studies in several sports have shown the benefits of adapting the playing environment to fit junior players. Frequently the changes are pragmatic choices based on space constraints or existing line markings, or the result of simple scaling based on stature. In this study, a method of scaling the cricket pitch length is presented which is based on the age-specific size and performance of the bowlers and batters. The objective was a pitch length which enabled young bowlers to bowl good length deliveries while releasing the ball at a more downward angle, similar to elite bowlers. The steeper release angle has the benefit of reducing the sensitivity of the ball flight distance to the variability of ball release. Based on data from county standard under-10 and under-11 players a pitch length of 16.22 yards (14.83 m) was calculated, 19% shorter than previously recommended for under-11s in England. A shorter pitch also increases the temporal challenge for batters, encouraging a wider variety of shots and improved anticipation skills. Pitch lengths scaled in this way to fit the players’ abilities as they develop will enable a more consistent ball release by bowlers and more consistent temporal demand for batters. 相似文献
8.
This study applied a vision-based tracking approach to the analysis of articulated, three-dimensional (3D) whole-body human
movements. A 3D computer graphics model of the human body was constructed from ellipsoid solids and customized to two gymnasts
for size and colour. The model was used in the generation of model images from multiple camera views with simulated environments
based on measurements taken on each of three synchronized video cameras and the lighting sources present in the original recording
environment. A hierarchical procedure was used whereby the torso was tracked initially to establish whole-body position and
orientation and subsequently body segments were added successively to the model to establish body configuration. An iterative
procedure was used at each stage to optimize each new set of variables using a score based on the RGB colour difference between
the model images and video images at each stage. Tracking experiments were carried out on movement sequences using both synthetic
and video image data. Promising qualitative results were obtained with consistent model matching in all sequences, including
sequences involving whole-body rotational movements. Accurate tracking results were obtained for the synthetic image sequences.
Automatic tracking results for the video images were also compared with kinematic estimates obtained via manual digitization
and favourable comparisons were obtained. It is concluded that with further development this model-based approach using colour
matching should provide the basis of a robust and accurate tracking system applicable to data collection for biomechanics
studies. 相似文献
9.
Michael J. Hiley Maurice R. Yeadon Emma Buxton 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):121-130
The Tkatchev on the high bar is a release and re-grasp skill in which the gymnast rotates in a direction during flight opposite to that of the preceding swing. Since the release window is defined as the time during which the gymnast has appropriate linear and angular momentum to ensure the bar can be re-grasped, it was speculated that the release windows for this skill would be smaller than for dismounts that are less constrained. One senior male gymnast competing at national standard performed 60 Tkatchev trials. A four-segment planar simulation model of the gymnast and high bar was used to determine the release windows in 10 successful and 10 unsuccessful performances of the Tkatchev recorded using a Vicon motion analysis system. Model parameters were optimized to obtain a close match between simulations and recorded performances in terms of rotation angle (1°), bar displacements (0.01 m), and release velocities (1%). Each matched simulation was used to determine the time window around the actual point of release for which the model had appropriate release parameters to complete the Tkatchev successfully. The release windows for the successful trials were small compared with those of dismounts. The unsuccessful trials were associated with later release and later timing of the actions at the shoulders and hips. 相似文献
10.
Photocell timing systems are used routinely to measure running speeds. In this study, the accuracy of such systems was evaluated using centre of mass speed estimates from three-dimensional video analysis as criteria. One subject ran at five nominal speeds (5-9 m x s(-1)) for each of five separations (1.6-2.4 m) between consecutive photocells. Running speeds were calculated from the photocell data using single beam and double beam systems. For single beam systems, the start of the first break of a beam and the start of the longest break of a beam were used as trigger criteria. For double beam systems, the first occurrence of both beams being broken and the start of the longest double break were used as trigger criteria. Root mean square speed errors were smaller for the double beam systems. The longest break criterion gave smaller root mean square errors than the first break criterion. In general, errors in speed were smaller for greater photocell separations. An error of 0.1 m x s(-1) was achieved using a single beam system set at hip height with a longest break criterion for photocell separations of around two stride lengths. The advantage of using a double beam system is that it achieves this accuracy without the need to adjust photocell separation for different stride lengths. 相似文献