Field and laboratory measurements of softball player swing speed and bat performance   总被引：1，自引：1，他引：0  

Lloyd Smith  Jeff Kensrud 《Sports Engineering》2014,17(2):75-82

The swing speed of the bat is one of the most important factors affecting the hit-ball speed. Most field studies tend to focus on measuring ball speed, which is easier to measure and quantify than bat speed. For this reason, relatively little data exist describing bat motion in field conditions. The following describes a relatively large swing speed field study involving bats of the same model with nearly constant weight and varying inertia. The study was conducted using right-handed batters on a regulation outdoor field with a live pitcher. Swing speed was measured by tracking markers on the bat with two high-speed video cameras so that the bat markers could be traced in three-dimensional space. The ball motion was tracked using the same high-speed video cameras and a three-dimensional Doppler radar system. Bat swing speed was observed to be proportional to the batter skill level and the normalised swing speed increased with decreasing bat inertia. The bat centre of rotation during impact was close to the knob of the bat. The bats were tested under controlled laboratory conditions using a standardised performance test. The field and laboratory results showed good agreement including the hit-ball speed and the subtle effect of bat inertia on the maximum performance location. The vibrational response of the bats was considered using modal analysis. The maximum performance location was correlated with the node of the first vibrational mode.  相似文献   

Commentary     

Lloyd Duck 《Educational Studies A Journal of the American Educational Studies Association》2013,49(3-4):500-503

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Substitution of ROTC for College Physical Education     

Lloyd Messersmith 《Research quarterly for exercise and sport》2013,84(3):325-326

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Understanding students’ experiences of professionalism learning: a ‘threshold’ approach     

Hilary Neve  Helen Lloyd  Tracey Collett 《Teaching in Higher Education》2017,22(1):92-108

Professionalism is a core element of curricula in many disciplines but can be difficult to teach and learn. This study used audio-diary methodology to identify professionalism threshold concepts in a small group learning setting in undergraduate medicine and to understand factors that might facilitate students to ‘get’ such concepts. Fifteen students and seven tutors kept audio-diaries over two terms. Data were analysed qualitatively for content. The key themes were then cross referenced to threshold concept criteria (e.g. where language indicated that learning was troublesome, integrative or transformative). Seven potential threshold concepts were identified which centred on students’ developing professional identities including working with uncertainty, considering the bigger picture, not needing to know everything and professional culture. Reflection on workplace experiences within a small group helped students ‘get’ these concepts. The study concludes that threshold concepts and audio-diaries are useful tools for understanding lived experiences of professionalism learning.  相似文献   

The long-term athlete development model: physiological evidence and application   总被引：2，自引：2，他引：0  

Ford P  De Ste Croix M  Lloyd R  Meyers R  Moosavi M  Oliver J  Till K  Williams C 《Journal of sports sciences》2011,29(4):389-402

Within the UK, the "Long Term Athlete Development" (LTAD) model has been proposed by a variety of national governing bodies to offer a first step to considering the approach to talent development. The model, which is primarily a physiological perspective, presents an advancement of understanding of developing athletic potential alongside biological growth. It focuses on training to optimize performance longitudinally, and considers sensitive developmental periods known as "windows of opportunity". However, it appears that there are a number of problems with this theoretical model that are not necessarily transparent to coaches. Principally, the model is only one-dimensional, there is a lack of empirical evidence upon which the model is based, and interpretations of the model are restricted because the data on which it is based rely on questionable assumptions and erroneous methodologies. Fundamentally, this is a generic model rather than an individualized plan for athletes. It is crucial that the LTAD model is seen as a "work in progress" and the challenge, particularly for paediatric exercise scientists, is to question, test, and revise the model. It is unlikely that this can be accomplished using classical experimental research methodology but this should not deter practitioners from acquiring valid and reliable evidence.  相似文献   

Monstrous Ecology: John Steinbeck,Ecology, and American Cultural Politics     

Lloyd Willis 《Journal of American culture (Malden, Mass. : 2003)》2005,28(4):357-367

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Unintended Consequences of Perfiormance Assessment: Issues of Bias and Fairness     

Lloyd Bond 《Educational Measurement》1995,14(4):21-24

Have advances in testing historically had unexpected consequences? How have African Americans fared on recent performance assessments? How can fairness of performance assessments be ensured?  相似文献   

Going beyond the buzzword: what exactly is CRM?     

Lloyd Alan Fletcher 《Learned Publishing》2001,14(3):213-222

Customer Relationship Management (CRM) is a business strategy for improving profitability by focusing on customer needs and creating an attentive relationship with the customer. It involves a personalized and interactive approach for the entire customer lifecycle. Successful implementation of a CRM approach requires changes in organization structure, culture, and skills, as well as front‐ and back‐office information systems. CRM is a hot topic at the moment, and the marketplace of ‘CRM solutions’ is rife with confusing jargon, grandiose claims, and marketing hyperbole. This article attempts to explain what CRM actually is (and isn't), and provides some suggestions for how you should approach CRM for your business.  相似文献   

PHILOSOPHY AND THE TEACHER     

Ed. D. I. Lloyd 《Educational Philosophy and Theory》1979,11(1):62-64

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Race and Sex Differences and Their Implications for Educational and Occupational Equality*     

Lloyd G. Humphreys 《Educational theory》1976,26(2):135-146

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