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In this paper, we present results on the measurement and analysis of the sound that is produced by the sharp impact loading of a golf ball by a flat massive object (e.g. the face of a golf club). We discuss: (a) the motivation for such a study; (b) some necessary background information on how golf balls vibrate; (c) the techniques used to acquire and analyse the data; and (d) an analysis of the sound made by dropping balls on a smooth, massive concrete target surface. These results establish a simple method for rapid and non-destructive measurement of the effective high-frequency elastic shear moduli of balls and ball cores. 相似文献
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In this paper, we report the discrete frequencies at which golf balls can vibrate, the mode patterns of these vibrations and how these modes can be excited. There are two broad classes of modes: those that radiate sound waves and those that do not. Both silent and acoustic modes are excited by tangential (i.e. spin-producing) impact forces; only acoustic modes are excited by radial impact forces. Exact analytical results for a homogeneous ball core are compared with finite element numerical results for both a core and a model two-piece ball. Correspondences are readily established for the important low-frequency modes, and the good agreement suggests the validity of these results for real golf balls. The results potentially provide the basis for a rapid, simple and non-destructive method of measuring the effective high-frequency elastic shear modulae of balls (and ball cores) as well as a method for 'tuning' the performance of balls for specific clubs. Some of these aspects are explored further in our companion paper in this issue. 相似文献
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JD Carpentieri 《European Journal of Education》2013,48(4):543-556
As literacy grows in importance, policymakers’ demands for programme quality grow, too. Evidence on the effectiveness of adult and family literacy programmes is limited at best: research gaps abound, and programme evaluations are more often than not based on flawed theories of programme impact. In the absence of robust evidence on the full range of short- and long-term programme impacts, it is difficult to accurately measure intervention effectiveness. Too frequently, researchers and policymakers focus only on short-term, easily measured outcomes, creating a ‘tyranny of effect size’ that may systematically underestimate impact while simultaneously distorting practice. However, the answer does not lie in turning away from quantitative research. Doing so will consign adult and family literacy to the margins of public policy, when they should be in the mainstream. Longitudinal research from Turkey and the US suggests a need for revised, more subtle theories of how adult literacy and family literacy programmes work, and the diverse ways they benefit participants. By working together more closely and intelligently, researchers, policymakers and practitioners can develop evaluation strategies that more accurately measure programme effects. The key is combining methodological rigour with fully fleshed out theories of literacy development and programme impact. 相似文献
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In this paper, we present results on the measurement and analysis of the sound that is produced by the sharp impact loading of a golf ball by a flat massive object (e.g. the face of a golf club). We discuss: (a) the motivation for such a study; (b) some necessary background information on how golf balls vibrate; (c) the techniques used to acquire and analyse the data; and (d) an analysis of the sound made by dropping balls on a smooth, massive concrete target surface. These results establish a simple method for rapid and non-destructive measurement of the effective high-frequency elastic shear moduli of balls and ball cores. 相似文献
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In this paper, we report the discrete frequencies at which golf balls can vibrate, the mode patterns of these vibrations and how these modes can be excited. There are two broad classes of modes: those that radiate sound waves and those that do not. Both silent and acoustic modes are excited by tangential (i.e. spin-producing) impact forces; only acoustic modes are excited by radial impact forces. Exact analytical results for a homogeneous ball core are compared with finite element numerical results for both a core and a model two-piece ball. Correspondences are readily established for the important low-frequency modes, and the good agreement suggests the validity of these results for real golf balls. The results potentially provide the basis for a rapid, simple and non-destructive method of measuring the effective high-frequency elastic shear modulae of balls (and ball cores) as well as a method for 'tuning' the performance of balls for specific clubs. Some of these aspects are explored further in our companion paper in this issue. 相似文献
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JD Hessinger 《海外英语》2007,(7):58-59
As on every weekday Tom Tuckett was awakened by his annoying, buzzing alarm clock at 5:30. He got out of bed and proceeded to his bathroom for his daily cold shower to wake him up. He turned the knob all the way to the right to make sure the water would be as cold as it could be. He had started this ritual when he moved to New York to take a teaching job at PS 181 in Manhattan. 相似文献