A review of tennis racket performance parameters     

Tom Allen  Simon Choppin  Duane Knudson 《Sports Engineering》2016,19(1):1-11

The application of advanced engineering to tennis racket design has influenced the nature of the sport. As a result, the International Tennis Federation has established rules to limit performance, with the aim of protecting the nature of the game. This paper illustrates how changes to the racket affect the player-racket system. The review integrates engineering and biomechanical issues related to tennis racket performance, covering the biomechanical characteristics of tennis strokes, tennis racket performance, the effect of racket parameters on ball rebound and biomechanical interactions. Racket properties influence the rebound of the ball. Ball rebound speed increases with frame stiffness and as string tension decreases. Reducing inter-string contacting forces increases rebound topspin. Historical trends and predictive modelling indicate swingweights of around 0.030–0.035 kg/m² are best for high ball speed and accuracy. To fully understand the effect of their design changes, engineers should use impact conditions in their experiments, or models, which reflect those of actual tennis strokes. Sports engineers, therefore, benefit from working closely with biomechanists to ensure realistic impact conditions.  相似文献   

Association between attitudes of filial responsibility and parent caregiving behavior     

Marines Aires  Duane Mocellin  Fernanda Laís Fengler Dal Pizzol  Carla Cristiane Becker Kottwitz Bierhals  Neena L. Chappell  Eliane Pinheiro de Morais 《Educational gerontology》2019,45(3):191-200

Objective: To analyze the association between attitudes of filial responsibility and adult child caregivers’ behaviors in the Southern Region of Brazil.

Methods: Cross-sectional study with 100 child caregivers of older adults. The data were collected through an interview using the protocol of filial responsibility adapted and validated to Brazilian Portuguese. Filial Expectation and Filial Piety scales evaluated the attitudes of filial responsibility. Caring behaviors assessed were: instrumental support, emotional, financial support, and companionship. The variables that presented p< .20 value in the bivariate analysis were inserted into a multivariate Poisson regression model.

Results: Financial and emotional support behaviors were significantly associated with filial piety (p = .050 and p = .001, respectively) and filial expectation (p = .013 and p = .023, respectively). Providing companionship was associated with filial piety (p = .015).

Conclusion: Attitudes of filial responsibility are associated with some but not all caregiving behaviors. Brazilians caring for older parents show more similarities to Chinese than to Canadian caregivers. Furthermore, filial responsibility and caregiving behaviors are strongly affected by Brazilian social and cultural norms. Reasons are discussed.  相似文献   

Comparison of student performance using web and paper‐based homework in college‐level physics     

Scott W. Bonham  Duane L. Deardorff  Robert J. Beichner 《科学教学研究杂志》2003,40(10):1050-1071

Homework gives students an opportunity to practice important college‐level physics skills. A switch to Web‐based homework alters the nature of feedback received, potentially changing the pedagogical benefit. Calculus‐ and algebra‐based introductory physics students enrolled in large paired lecture sections at a public university completed homework of standard end‐of‐the‐chapter exercises using either the Web or paper. Comparison of their performances on regular exams, conceptual exams, quizzes, laboratory, and homework showed no significant differences between groups; other measures were found to be strong predictors of performance. This indicates that the change in medium itself has limited effect on student learning. Ways in which Web‐based homework could enable exercises with greater pedagogical value are discussed. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 1050–1071, 2003  相似文献   

FULL CIRCUIT: FROM OPEN‐ TO CLOSED‐ AND BACK     

Duane B. Starcher 《Learning, Media and Technology》1981,7(2):45-47

Memorial University has been active in the use of educational media since its creation, and operates a public channel, initially broadcast through CBC but now on cable distribution. The author discusses the changes that have occurred over the past few years in the role of television there and describes the interactive element called PLA YBA CK, through which viewers can now access any of 1000 programmes by a telephone call to the control room. The reader is invited to consider the changes in philosophy such developments inevitably entail.  相似文献   

Freud's America     

Duane Vorhees 《Journal of American culture (Malden, Mass. : 2003)》1989,12(4):43-52

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Qualitative biomechanical principles for application in coaching   总被引：1，自引：0，他引：1  

Knudson D 《Sports biomechanics / International Society of Biomechanics in Sports》2007,6(1):109-118

Many aspects of human movements in sport can be readily understood by Newtonian rigid-body mechanics. Many of these laws and biomechanical principles, however, are counterintuitive to a lot of people. There are also several problems in the application of biomechanics to sports, so the application of biomechanics in the qualitative analysis of sport skills by many coaches has been limited. Biomechanics scholars have long been interested in developing principles that facilitate the qualitative application of biomechanics to improve movement performance and reduce the risk of injury. This paper summarizes the major North American efforts to establish a set of general biomechanical principles of movement, and illustrates how principles can be used to improve the application of biomechanics in the qualitative analysis of sport technique. A coach helping a player with a tennis serve is presented as an example. The standardization of terminology for biomechanical principles is proposed as an important first step in improving the application ofbiomechanics in sport. There is also a need for international cooperation and research on the effectiveness of applying biomechanical principles in the coaching of sport techniques.  相似文献   

How lsu builta computer-education program for prospective teachers from the ground up     

Duane K. Troxel 《TechTrends》1985,30(5):28-30

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Cupertino boca raton     

Duane K. Troxel  Jim Chiavacci 《TechTrends》1985,30(6):10-19

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Use of deterministic models in sports and exercise biomechanics research     

Chow JW  Knudson DV 《Sports biomechanics / International Society of Biomechanics in Sports》2011,10(3):219-233

A deterministic model is a modeling paradigm that determines the relationships between a movement outcome measure and the biomechanical factors that produce such a measure. This review provides an overview of the use of deterministic models in biomechanics research, a historical summary of this research, and an analysis of the advantages and disadvantages of using deterministic models. The deterministic model approach has been utilized in technique analysis over the last three decades, especially in swimming, athletics field events, and gymnastics. In addition to their applications in sports and exercise biomechanics, deterministic models have been applied successfully in research on selected motor skills. The advantage of the deterministic model approach is that it helps to avoid selecting performance or injury variables arbitrarily and to provide the necessary theoretical basis for examining the relative importance of various factors that influence the outcome of a movement task. Several disadvantages of deterministic models, such as the use of subjective measures for the performance outcome, were discussed. It is recommended that exercise and sports biomechanics scholars should consider using deterministic models to help identify meaningful dependent variables in their studies.  相似文献   

Terms and nomenclature     

Winter EM  Knudson DV 《Journal of sports sciences》2011,29(10):999-1000

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