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321.
Lloyd V. Smith 《Sports Engineering》2014,17(3):123-130
This study considered the effect of temperature and relative humidity on the performance of softballs, baseballs and bats. The balls were conditioned in constant humidity and temperature environments and then impacted against a rigidly supported load cell from which the ball coefficient of restitution and stiffness were obtained. The balls reached steady state temperature on the order of a few minutes, while steady state humidity required upwards of 2 weeks. Ball stiffness and coefficient of restitution tended to decrease with increasing humidity. Increasing temperature generally caused ball stiffness to decrease and the coefficient of restitution to increase. Balls made from synthetic materials tended to resist the effects of moisture, but showed an increased sensitivity to temperature. The effect of temperature and humidity on bat performance (sign and magnitude) depended on the design of the ball and bat. The largest effect occurred in professional baseball, where for a long fly ball, decreasing the temperature by 33 °C and lowering the relative humidity from 90 to 10 % resulted in a 5 m decrease and a 15 m increase in hit distance, respectively. 相似文献
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With an increasing focus on knowledge mobilisation, there is a concomitant shift in how stakeholders, such as parents, ought to be engaged in the research process. The purpose of this study was to explore the research priorities of parents of Kindergarten to Grade 12 students with learning exceptionalities and disabilities in British Columbia, Canada. A cross-sectional survey design was employed. A convenience sample of 130 parents completed the survey. From a list of pre-selected variables, parents identified time to initial designation, high school graduation, and home-schooling/independent schooling as the three most important research priorities, with learning disabilities, autism spectrum disorder, and moderate behaviour support/mental illness as the three most important designations. In an open-ended response, parents recommended further areas for inquiry, including the effectiveness of inclusive education and school exclusion. Research priority setting can help create research agendas that align with the needs and interests of stakeholders. 相似文献