Variability in clubhead presentation characteristics and ball impact location for golfers' drives     

Betzler NF  Monk SA  Wallace ES  Otto SR 《Journal of sports sciences》2012,30(5):439-448

The purpose of the present study was to analyse the variability in clubhead presentation to the ball and the resulting ball impact location on the club face for a range of golfers of different ability. A total of 285 male and female participants hit multiple shots using one of four proprietary drivers. Self-reported handicap was used to quantify a participant's golfing ability. A bespoke motion capture system and user-written algorithms was used to track the clubhead just before and at impact, measuring clubhead speed, clubhead orientation, and impact location. A Doppler radar was used to measure golf ball speed. Generally, golfers of higher skill (lower handicap) generated increased clubhead speed and increased efficiency (ratio of ball speed to clubhead speed). Non-parametric statistical tests showed that low-handicap golfers exhibit significantly lower variability from shot to shot in clubhead speed, efficiency, impact location, attack angle, club path, and face angle compared with high-handicap golfers.  相似文献   

Effects of golf shaft stiffness on strain, clubhead presentation and wrist kinematics     

Betzler NF  Monk SA  Wallace ES  Otto SR 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(2):223-238

The aim of this study was to quantify and explain the effect of shaft stiffness on the dynamics of golf drives. Twenty golfers performed swings with two clubs designed to differ only in shaft bending stiffness. Wrist kinematics and clubhead presentation to the ball were determined using optical motion capture systems in conjunction with a radar device for capturing ball speed, launch angle, and spin. Shaft stiffness had a marginally small effect on clubhead and ball speeds, which increased by 0.45% (p < 0.001) and 0.7% (p = 0.008), respectively, for the less stiff club. Two factors directly contributed to these increases: (i) a faster recovery of the lower flex shaft from lag to lead bending just before impact (p < 0.001); and (ii) an increase of 0.4% in angular velocity of the grip of the lower flex club at impact (p = 0.003). Unsurprisingly, decreases in shaft stiffness led to more shaft bending at the transition from backswing to downswing (p < 0.001). Contrary to previous research, lead bending at impact marginally increased for the stiffer shaft (p = 0.003). Overall, and taking effect sizes into account, the changes in shaft stiffness in isolation did not have a meaningful effect on the measured parameters, for the type of shaft investigated.  相似文献   

Personal and systems‐level factors that limit and facilitate school psychologists' involvement in school‐based mental health services     

Shannon M. Suldo  Allison Friedrich  Jessica Michalowski 《Psychology in the schools》2010,47(4):354-373

The common path through which youth with mental health problems actually receive treatment is the education system. The current study used qualitative methodology to explore why school psychologists are not providing the level of mental health services that children need, leaders in the field call for, and practitioners desire. Thirty‐nine school psychologists participated in 11 focus groups; they responded to structured questions regarding the range of mental health services they currently provide, as well as the personal and systemic factors that facilitate and limit their provision of these mental health services. Analysis of themes that emerged across focus groups indicated that school psychologists provide a broad variety of mental health services with an emphasis on group and individual counseling as well as crisis intervention. The factors most often mentioned as prohibiting the delivery of such services included problems inherent to using schools as the site for service delivery, insufficient training, and a lack of support from department/district administration and school personnel. The enabling conditions that emerged most involved perceptions of ample support from administration and school personnel, sufficient integration into the school site, and particular personal characteristics, such as the desire to provide counseling and the ability to maintain personal boundaries. Implications for practitioners, administrators, and trainers are discussed. © 2010 Wiley Periodicals, Inc.  相似文献   

卡尔斯鲁厄物理课程     

F.赫尔曼  陈敏华 《物理教学探讨》2015,(4):1-4

卡尔斯鲁厄物理课程试图通过消除传统概念、重新建构内容和广泛运用实物模型来促使物理课程的现代化。该课程在欧洲已被试用了二十多年,并经过了试验和修改;在中国已被试用了近八年。本文将介绍该课程的结构,并讨论在物理学各分支学科中的相关教学问题。  相似文献   

Influence of shaft length on golf driving performance     

Kenny IC  Wallace ES  Otto SR 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(3):322-332

The aim of this study was to determine how shaft length affects golf driving performance. A range of drivers with lengths between 1.168 m and 1.270 m, representing lengths close to the 1.219 m limit imposed by R&A Rules Limited (2008), were assembled and evaluated. Clubhead and ball launch conditions and drive distance and accuracy were determined for seven category 1 golfers (handicaps 0.21 +/- 2.41) who performed shots on a purpose-built practice hole. As shaft length increased from 1.168 m to 1.270 m, initial ball velocity increased (+ 1.8 m/s, P < 0.01). Ball carry (+ 4.3 m, P = 0.152) also increased, although not significantly so. Furthermore, as shaft length increased, for all club comparisons there was no decrease in accuracy. Ball launch conditions of spin components and launch angle remained unaffected by shaft length. Launch angle increased (0.8 degree, F = 1.074, P = 0.362) as driver shaft length increased. Our results show that clubhead and ball velocity together with ball carry tended to increase with no loss of accuracy.  相似文献   

National Case Studies/Etudes de cas nationaux     

Friedrich Buchberger 《欧洲师范教育杂志》1992,15(1-2):87-96

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Prospektive Pädagogik     

Friedrich Schneider 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1958,4(1):36-50

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Kurze Geschichte der Internationalen Zeitschrift für Erziehungswissenschaft     

Friedrich Schneider 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1963,8(3-4):416-417

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Stichwort: Interferenz von Religion und Bildung     

Friedrich?SchweitzerEmail author 《Zeitschrift für Erziehungswissenschaft》2004,7(3):313-325

Ohne Zusammenfassung  相似文献   

Obituary     

Friedrich Schweitzer 《British Journal of Religious Education》2015,37(1):111-116

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