Dynamics of the basketball shot with application to the free throw     

Okubo H  Hubbard M 《Journal of sports sciences》2006,24(12):1303-1314

A completely general three-dimensional dynamic model is presented for the motion of basketball shots that may contact the rim, the backboard, the bridge between the rim and board, and possibly the board and the bridge simultaneously. Non-linear ordinary differential equations with six degrees of freedom describe the ball angular velocity and ball centre position. The model includes radial ball compliance and damping and contains five sub-models: purely gravitational flight, and ball-rim, ball-bridge, ball-board, and ball-bridge-board contact. Each contact sub-model has both slipping and non-slipping motions. Switching between the sub-models depends on the reaction force at, and velocity of, the contact point. Although the model can be used to study shots from any point on the court, we here use it to study the sets of free throw release angle, velocity, angular velocity, and lateral deviation angle that result in success (capture), as well as underhand free throws and those using an under-inflated ball. Free throw shots with larger backspin, lower inflation pressures, and underhand release conditions are shown to result in larger capture percentages.  相似文献   

The relationship between peak height velocity and physical performance in youth soccer players   总被引：1，自引：1，他引：0  

Philippaerts RM  Vaeyens R  Janssens M  Van Renterghem B  Matthys D  Craen R  Bourgois J  Vrijens J  Beunen G  Malina RM 《Journal of sports sciences》2006,24(3):221-230

Longitudinal changes in height, weight and physical performance were studied in 33 Flemish male youth soccer players from the Ghent Youth Soccer Project. The players' ages at the start of the study ranged from 10.4 to 13.7 years, with a mean age of 12.2 +/- 0.7 years. Longitudinal changes were studied over a 5 year period. Peak height velocity and peak weight velocity were determined using non-smoothed polynomials. The estimations of peak height velocity, peak weight velocity and age at peak height velocity were 9.7 +/- 1.5 cm x year-1, 8.4 +/- 3.0 kg x year-1 and 13.8 +/- 0.8 years, respectively. Peak weight velocity occurred, on average, at the same age as peak height velocity. Balance, speed of limb movement, trunk strength, upper-body muscular endurance, explosive strength, running speed and agility, cardiorespiratory endurance and anaerobic capacity showed peak development at peak height velocity. A plateau in the velocity curves was observed after peak height velocity for upper-body muscular endurance, explosive strength and running speed. Flexibility exhibited peak development during the tear after peak height velocity. Trainers and coaches should be aware of the individual characteristics of the adolescent growth spurt and the training load should also be individualized at this time.  相似文献   

Quantum algorithms: A?survey of some recent results     

Martin R?tteler 《Informatik - Forschung und Entwicklung》2006,55(3):3-20

Quantum algorithms are a field of growing interest within the theoretical computer science as well as the physics community. Surprisingly, although the number of researchers working on the subject is ever-increasing, the number of quantum algorithms found so far is quite small. In fact, the task of designing new quantum algorithms has been proven to be extremely difficult. In this paper we give an overview of the known quantum algorithms and briefly describe the underlying ideas. Roughly, the algorithms presented are divided into hidden subgroup type algorithms and in amplitude amplification type algorithms. While the former deal with problems of group-theoretical nature and have the promise to yield strong separations of classical and quantum algorithms, the latter have been proved to be a prolific source of algorithms in which a polynomial speed-up as compared to classical algorithms can be achieved. We also discuss quantum algorithms which do not fall under these two categories and give a survey of techniques of general interest in quantum computing such as adiabatic computing, lower bounds for quantum algorithms, and quantum interactive proofs.  相似文献   

Puberty and physical self-perceptions of competitive female figure skaters: an interdisciplinary approach   总被引：1，自引：0，他引：1  

Monsma EV  Malina RM  Feltz DL 《Research quarterly for exercise and sport》2006,77(2):158-166

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青少年跳高赛前控制训练的实验研究     

宋允清 《浙江体育科学》2001,23(4):4-6

为了探讨跳高赛前控制训练这一课题，我们运用运动训练学的基本原理，采用随训跟踪的方法．对其进行了实验探讨，旨在摸索跳高赛前控制训练的一般规律，为青少年跳高的科学化训练积累经验。  相似文献   

Sektion Historische Bildungsforschung     

Petra G?tte 《Zeitschrift für Erziehungswissenschaft》2006,17(33):129-137

Ohne Zusammenfassung  相似文献   

The written composing ability of children with learning disabilities: a review of the literature from 1980 to 1990.     

P L Newcomer  E M Barenbaum 《Journal of learning disabilities》1991,24(10):578-593

This article reviews the literature pertaining to the written composing ability of students with learning disabilities that was published primarily in the decade from 1980 to 1990. The papers included are either reports of research or discussions of instructional procedures that are based on research. The topics addressed include story composition, expository writing, training/intervention research, and rationales/procedures for instruction.  相似文献   

Editors' Foreword     

Kathy Merlock Jackson  William M. Jones 《Journal of American culture (Malden, Mass. : 2003)》2004,27(2):129-129

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Editorial     

Rosalind M.O. Pritchard 《Higher Education Quarterly》2001,55(3):235-238

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Resources on the Internet for Engineering Education     

M. BHATT 《European Journal of Engineering Education》1996,21(3):235-243

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