共查询到20条相似文献，搜索用时 31 毫秒
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Experimental and theoretical research in archery 总被引：1，自引：0，他引：1
R Pekalski 《Journal of sports sciences》1990,8(3):259-279
The aim of this study was to introduce certain methods and research techniques and to present the results of experiments on parameters of archery equipment to optimize the interaction of the archer-bow-arrow system's elements. In order to achieve the research requirements, the following were devised: 1. A mathematical model of an arrow's movement during its interaction with a bow. 2. A mechanical model of an archer-bow-arrow system, which constitutes a device for mechanical loosing of an arrow from the bow strings (DMLA). 3. Three series of high-speed filming. The mathematical model and computer simulation were used to describe the arrow's movement for various initial conditions and various parameters of the equipment, based on which a nomogram was constructed of the optimum arrow parameters for bows of various draw forces. The device for the mechanical loosing of arrows from a bow was used to study the influence of selected parameters of the archer-bow-arrow system on the accuracy of shots. The film analysis was used to verify the mathematical and mechanical models constructed. 相似文献
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Ihor Zanevsky 《Sports Engineering》2006,9(2):77-86
Competition results in sport archery depend to a great extent upon the optimal combination of bow-arrow-archer system parameters.
A significant part of bow tuning is vertical adjustment, the aim of which is to give an arrow zero angle of attack. It is
conducted in a long and complicated manner and error correction takes a lot of time and effort. The goal of the research was
to create an analytical method to determine an optimal combination of bow parameters, which ensures zero angle of attack for
an arrow launched from a string. Mechanical and mathematical models of bow and arrow geometry in the vertical plane in braced
and drawn situations were investigated. An asymmetrical scheme, rigid beams, concentrated elastic elements and elastic string
were the main features of the model. Numerical results of a computer simulation are presented in tabular and graphical form,
which makes it easy for sportsmen and coaches to use. 相似文献
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Marko Tiermas 《Sports Engineering》2017,20(2):155-162
An extended offset-eccentric model of an archery twin-round-wheel compound bow is derived. Varying some parameters of the model, the respective effects on the calculated force–draw curve are considered. Two static quality coefficients for the compound bow are introduced. It was found that the twin-round-wheel compound bow can be designed to be more energetic with the help of the model. For a bow with some modifications 18.5% increment of energy was calculated. Also a theoretical limit for the force–draw curve of the compound bow is concluded. 相似文献
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Isabelle Rogowski Thomas Creveaux Cyril Genevois Shahnaz Klouche Michel Rahme Philippe Hardy 《European Journal of Sport Science》2016,16(4):483-489
The purpose of this study was to examine the relationship between the upper limb anthropometric dimensions and a history of dominant upper limb injury in tennis players. Dominant and non-dominant wrist, forearm, elbow and arm circumferences, along with a history of dominant upper limb injuries, were assessed in 147 male and female players, assigned to four groups based on location of injury: wrist (n = 9), elbow (n = 25), shoulder (n = 14) and healthy players (n = 99). From anthropometric dimensions, bilateral differences in circumferences and in proportions were calculated. The wrist group presented a significant bilateral difference in arm circumference, and asymmetrical bilateral proportions between wrist and forearm, as well as between elbow and arm, compared to the healthy group (6.6 ± 3.1% vs. 4.9 ± 4.0%, P < 0.01; ?3.6 ± 3.0% vs. ?0.9 ± 2.9%, P < 0.05; and ?2.2 ± 2.2% vs. 0.1 ± 3.4%, P < 0.05, respectively). The elbow group displayed asymmetrical bilateral proportions between forearm and arm compared to the healthy group (?0.4 ± 4.3% vs. 1.5 ± 4.0%, P < 0.01). The shoulder group showed significant bilateral difference in elbow circumference, and asymmetrical bilateral proportions between forearm and elbow when compared to the healthy group (5.8 ± 4.7% vs. 3.1 ± 4.8%, P < 0.05 and ?1.7 ± 4.5% vs. 1.4 ± 4.3%, P < 0.01, respectively). These findings suggest that players with a history of injury at the upper limb joint present altered dominant upper limb proportions in comparison with the non-dominant side, and such asymmetrical proportions would appear to be specific to the location of injury. Further studies are needed to confirm the link between location of tennis injury and asymmetry in upper limb proportions using high-tech measurements in symptomatic tennis players. 相似文献
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综合运用文献研究与考古文物资料分析相结合的方法,辅以射箭运动的基本训练学规律与传统弓箭制作之田野实证,对新疆地区两种出土角弓进行考释。得出如下结论:弓弰翻卷的连弧蛇形角弓是斯基泰人基于骑马游牧的传统、野兽崇拜的心理、便利的北山羊角取材,在继承了亚述三角弓“翻卷的弓弰”设计理念后的革故鼎新;弓渊宽阔,弓弣微凹的插接型长弰角弓起源于公元前2世纪的帕提亚帝国。随着丝绸之路的贯通,交流频度与交流速度的激增使该器形迅速为整个欧亚大陆的民族所复刻。其中,中华文明赋予了其最重要的文化内涵,使原本用于战争的武器有了超越物态的“礼”的象征意义。 相似文献
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The following research approximated how the central nervous system of Paralympic wheelchair athletes resolve kinematic redundancies during upper-limb movements. A multibody biomechanical model of a tetraplegic Paralympic athlete was developed using subject-specific body segment parameters. The angular joint kinematics throughout a specified Paralympic sport movement (i.e., wheelchair curling) were experimentally measured using inertial measurement units. The motor control system of the Paralympian was mathematically modelled and simulated using forward dynamics optimization. The predicted kinematics from different optimization objective functions (i.e., minimizing resultant joint moments, mechanical joint power, and angular joint velocities and accelerations) were compared with those experimentally measured throughout the wheelchair curling movement. Of the optimization objective functions under consideration, minimizing angular joint accelerations produced the most accurate predictions of the kinematic trajectories (i.e., characterized with the lowest overall root mean square deviations) and the shortest optimization computation time. The implications of these control findings are discussed with regards to optimal wheelchair design through predictive dynamic simulations. 相似文献
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Yi Y. Lim Thorsten Sterzing Crosby J.Y. Teo Rebecca Alonzo Jing W. Pan Phillis S.P. Teng 《Journal of sports sciences》2020,38(14):1605-1614
ABSTRACT This study investigated the between-limb asymmetry in kinetic and temporal characteristics during bilateral plyometric drop jumps from different heights. Seventeen male basketball players performed drop jumps from 3 heights on two platforms in randomized orders. Vertical ground reaction force data were analysed with respect to the lead limb (i.e. the limb stepping off the raised platform first) and trail limb. Peak forces and loading rates of each limb were calculated. The absolute time differential between the two limbs at initial ground contact and takeoff were determined. The frequency of symmetrical landing and taking off with “both limbs together” were counted using 3 time windows. Results showed that the lead limb displayed higher peak forces and loading rates than the trail limb across all heights (p <.05). As drop height increased, the absolute time differentials decreased at initial ground contact (p <.001) but increased at takeoff (p =.035). The greater the preset time window, the more landings and takeoffs were classified as bilaterally symmetrical. In conclusion, higher drop heights allowed subjects to become more bilaterally symmetrical in the timing of landing but this reduction in temporal asymmetry did not accompany with any reduction in kinetic asymmetry. 相似文献
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A forward dynamics computer simulation for replicating tennis racket/ball impacts is described consisting of two rigid segments
coupled with two degrees of rotational freedom for the racket frame, nine equally spaced point masses connected by 24 visco-elastic
springs for the string-bed and a point mass visco-elastic ball model. The first and second modal responses both in and perpendicular
to the racket string-bed plane have been reproduced for two contrasting racket frames, each strung at a high and a low tension.
Ball/string-bed normal impact simulations of real impacts at nine locations on each string-bed and six different initial ball
velocities resulted in <3% RMS error in rebound velocity (over the 16–27 m/s range observed). The RMS difference between simulated
and measured oblique impact rebound angles across nine impact locations was 1°. Thus, careful measurement of ball and racket
characteristics to configure the model parameters enables researchers to accurately introduce ball impact at different locations
and subsequent modal response of the tennis racket to rigid body simulations of tennis strokes without punitive computational
cost. 相似文献
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中国军人体质的评价标准与综合评价方法 总被引：3，自引：0，他引：3
利用百分位数法为所选指标制定评分标准,并在此基础上利用逐步回归分析的方法建立体质综合评价的数学模型,对军人体质综合评价方法进行了探索。在各项指标贡献率的确定上,采用的是经逐步回归分析得来的“标准化偏回归系数”与“简单相关系数”的乘积。在对每一个样本各项选中指标进行评分之后,进行逐步回归分析,建立了体质总体、身体形态、身体机能、身体素质、有氧耐力和力量素质共6种体质评价的数学模型。这些模型的建立以及评价标准的制定为计算机评价系统的实现提供了基本算法,也为《中国军人体质评价系统软件》的开发提供了可能。 相似文献
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运用生物力学特性和组织学手段 建立动物训练模型的研究 总被引：1，自引：0，他引：1
周思红 《西安体育学院学报》2002,19(4):35-37
为了建立动物模型 ,笔者选用S D大鼠进行游泳训练 ,大鼠经 6周渐增负荷训练后 ,测取了大鼠左侧腓肠肌强度极限、肌肉最大伸长量、肌肉弹性刚度和肌肉断裂能密度等力学指标 ,同时进行了组织学实验 ,即电镜与光镜观察 ,建立了动物训练模型 相似文献
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本文以新疆锡伯族传统弓箭文化的产业化为主要对象,通过阅读相关的书籍资料,得出锡伯族弓箭文化的发展历史及濒危现状,调查研究理清发展脉络,对存在的问题进行分析,并提出非物质文化遗产项目的顺利运作和政府推动民间组织的"三角模式"互动机制是弓箭文化产业化的重要发展对策。研究结果显示,弓箭文化产业化公司的成立在市场中占据很大的优势地位,建立弓箭文化产业化公司同时也在传承和保护锡伯族濒危的弓箭文化,对于国家级非物质遗产保护项目也有着重要的作用。 相似文献
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Abstract The 'stiffness' concept originates from Hooke's law which states that the force required to deform an object is related to a spring constant and the distance that object is deformed. Research into stiffness in the human body is undergoing unprecedented popularity; possibly because stiffness has been associated with sporting performance and some lower limb injuries. However, some inconsistencies surrounding stiffness measurement exists bringing into question the integrity of some research related to stiffness. The aim of this study was to review literature which describes how vertical, leg and knee stiffness has been measured in adult populations while running, jumping or hopping. A search of the entire MEDLINE, PubMed and SPORTDiscus databases and an iterative reference check was performed. Sixty-seven articles were retrieved; 21 measured vertical stiffness, 51 measured leg stiffness, and 22 measured knee stiffness. Thus, some studies measured several 'types' of stiffness. Vertical stiffness was typically the quotient of ground reaction force and centre of mass displacement. For leg stiffness it was and change in leg length, and for the knee it was the quotient of knee joint moments and change in joint angle. Sample size issues and measurement techniques were identified as limitations to current research. 相似文献
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Benjamin G. Serpell Nick B. Ball Jennie M. Scarvell Paul N. Smith 《Journal of sports sciences》2013,31(13):1347-1363
Abstract The ‘stiffness’ concept originates from Hooke's law which states that the force required to deform an object is related to a spring constant and the distance that object is deformed. Research into stiffness in the human body is undergoing unprecedented popularity; possibly because stiffness has been associated with sporting performance and some lower limb injuries. However, some inconsistencies surrounding stiffness measurement exists bringing into question the integrity of some research related to stiffness. The aim of this study was to review literature which describes how vertical, leg and knee stiffness has been measured in adult populations while running, jumping or hopping. A search of the entire MEDLINE, PubMed and SPORTDiscus databases and an iterative reference check was performed. Sixty-seven articles were retrieved; 21 measured vertical stiffness, 51 measured leg stiffness, and 22 measured knee stiffness. Thus, some studies measured several ‘types’ of stiffness. Vertical stiffness was typically the quotient of ground reaction force and centre of mass displacement. For leg stiffness it was and change in leg length, and for the knee it was the quotient of knee joint moments and change in joint angle. Sample size issues and measurement techniques were identified as limitations to current research. 相似文献
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Daniel F. B. Haeufle Jay Worobets Ian Wright Jenny Haeufle Darren Stefanyshyn 《Sports Engineering》2012,15(4):215-220
A common belief in the golf community is that a lighter shaft allows the golfer to swing the club faster. From a mechanical point of view, reducing the mass of the shaft would result in a faster swing. However, a golfer is not a purely mechanical system, and so it is simplistic to assume that identical loads will be applied when swinging different clubs. Therefore, the purpose of this study was to test the hypothesis that golfers behave similar to a mechanical model when swinging clubs of varying mass. A torque driven model estimated the effects caused by the addition of 22?g to the shaft. Twelve golfers hit balls with a standard driver as well as a driver fitted with the same 22?g increase in mass. Club kinematics were collected with a high-speed motion capture system. The model predicted a 1.7?% lower club head speed for the club with additional mass. One subject showed a similar reduction (1.4?%), but one subject showed an increase in club head speed by 3.0?%. Ten subjects did not show any significant differences. These results suggest that golfers do not respond to changes in club mass in a mechanically predictable way. 相似文献
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