矩阵方法在点的合成运动中的应用     

樊新权 《贵州教育学院学报》2004,15(2):20-21,35

用矩阵方法对点的合成运动进行分析、研究，推导出求解点的合成运动的矩阵计算公式，这些公式有助于理论力学在计算机上的应用，并对提高理论力学的教学质量可起到积极的作用。  相似文献   

乒乓球运动员以预防损伤为主的功能训练          下载免费PDF全文

李男  叶晶龙 《体育科研》2019,(5):95-98

功能训练的理念来源于康复领域，现已逐步应用到运动训练中。由于乒乓球运动的项目特征，乒乓球运动员肩关节、腰椎关节、膝关节、踝关节、腕关节等部位容易出现运动损伤。通过对乒乓球运动员常出现的功能问题进行分析，寻找存在的常见问题，进而提出相应的功能训练建议。乒乓球运动员可根据情况，增加改善肩关节、胸椎关节、髋关节、踝关节的活动范围的训练，提高肩胛骨、核心和下肢稳定性的训练，以及改善肩袖、躯干肌力不平衡的训练，通过针对性的功能训练有效减少乒乓球运动员损伤的发生。  相似文献   

Kinematic analysis of hip and knee rotation and other contributors to ballet turnout     

Amy E. Quanbeck  Sara C. Handley  Deborah S. Quanbeck 《Journal of sports sciences》2017,35(4):331-338

Turnout, or external rotation (ER) of the lower extremities, is essential in ballet. The purpose of this study was to utilise physical examination and a biomechanical method for obtaining functional kinematic data using hip and knee joint centres to identify the relative turnout contributions from hip rotation, femoral anteversion, knee rotation, tibial torsion, and other sources. Ten female dancers received a lower extremity alignment assessment, including passive hip rotation, femoral anteversion, tibial torsion, weightbearing foot alignment, and Beighton hypermobility score. Next, turnout was assessed using plantar pressure plots and three-dimensional motion analysis; participants performed turnout to ballet first position on both a plantar pressure mat and friction-reducing discs. A retro-reflective functional marker motion capture system mapped the lower extremities and hip and knee joint centres. Mean total turnout was 129±15.7° via plantar pressure plots and 135±17.8° via kinematics. Bilateral hip ER during turnout was 49±10.2° (36% of total turnout). Bilateral knee ER during turnout was 41±5.9° (32% of total turnout). Hip ER contribution to total turnout measured kinematically was less than expected compared to other studies, where hip ER was determined without functional kinematic data. Knee ER contributed substantially more turnout than expected or previously reported. This analysis method allows precise assessment of turnout contributors.  相似文献   

Kinematic and kinetic analysis of overhand,sidearm and underhand lacrosse shot techniques     

Charles A. J. Macaulay  Pro Stergiou  Darren Stefanyshyn  Luciano Tomaghelli 《Journal of sports sciences》2017,35(23):2350-2356

Lacrosse requires the coordinated performance of many complex skills. One of these skills is shooting on the opponents’ net using one of three techniques: overhand, sidearm or underhand. The purpose of this study was to (i) determine which technique generated the highest ball velocity and greatest shot accuracy and (ii) identify kinematic and kinetic variables that contribute to a high velocity and high accuracy shot. Twelve elite male lacrosse players participated in this study. Kinematic data were sampled at 250 Hz, while two-dimensional force plates collected ground reaction force data (1000 Hz). Statistical analysis showed significantly greater ball velocity for the sidearm technique than overhand (P < 0.001) and underhand (P < 0.001) techniques. No statistical difference was found for shot accuracy (P > 0.05). Kinematic and kinetic variables were not significantly correlated to shot accuracy or velocity across all shot types; however, when analysed independently, the lead foot horizontal impulse showed a negative correlation with underhand ball velocity (P = 0.042). This study identifies the technique with the highest ball velocity, defines kinematic and kinetic predictors related to ball velocity and provides information to coaches and athletes concerned with improving lacrosse shot performance.  相似文献   

基于多普勒频谱图的力量项目运动员左室舒张期室壁运动研究     

张戈  李献震  田金凯 《吉林体育学院学报》2016,(1):57-61

通过测定和比较正常人和力量项目运动员在静息和逐级递增负荷运动时，室壁多普勒频谱图上E波和A波峰值速度，研究左室后壁主动松弛和被动充盈功能的变化。结果表明：在静息状态，力量项目组房缩期心房收缩对于左室舒张充盈的贡献小于正常组；在逐级递增负荷中，力量项目组心脏舒张功能的动员表现为同时动用主动舒张储备和左房收缩储备，显示出心脏主动舒张的能力强，左房收缩储备大。  相似文献   

Smart structures and materials     

V. K. Wadhawan 《Resonance》2005,10(11):27-41

A structure is an assembly that serves an engineering function. It is reasonable to expect that all engineering design should be smart, and not dumb. But one can still make a distinction between smartly designed structures and smart structures. The latter term has acquired a specific technical meaning over the last few decades. A smart structure is that which has the ability to respond adaptively in a pre-designed useful and efficient manner to changes in environmental conditions, including any changes in its own condition; the response is adaptive in the sense that two or more stimuli or inputs may be received as anticipated and yet there is a single response function as per design. Smartness ensures that the structure gives optimum performance under a variety of environmental conditions. While structures with some degree of smartness have been designed from times immemorial, the current activity and excitement in this field derives its impetus from the level of sophistication achieved in materials science, information technology, measurement science, sensors, actuators, signal processing, nanotechnology, cybernetics, artificial intelligence, and biomimetics.  相似文献   

质点组内力的功改变质心动能的条件     

田志川 《通化师范学院学报》2003,24(6):25-26

讨论了质点组内力的功是可以改变质心动能的，以及所满足的条件．  相似文献   

Comparison of impact forces,accelerations and ankle range of motion in surfing-related landing tasks     

Lina E. Lundgren  Tai T. Tran  Sophia Nimphius  Ellen Raymond  Josh L. Secomb  Oliver R.L. Farley 《Journal of sports sciences》2016,34(11):1051-1057

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Hip and upper extremity kinematics in youth baseball pitchers     

Taylor Holt 《Journal of sports sciences》2016,34(9):856-861

The purpose of this study was to examine the relationship between dynamic hip rotational range of motion and upper extremity kinematics during baseball pitching. Thirty-one youth baseball pitchers (10.87 ± 0.92 years; 150.03 ± 5.48 cm; 44.83 ± 8.04 kg) participated. A strong correlation was found between stance hip rotation and scapular upward rotation at maximum shoulder external rotation (r = 0.531, P = 0.002) and at ball release (r = 0.536, P = 0.002). No statistically significant correlations were found between dynamic hip rotational range of motion and passive hip range of motion. Hip range of motion deficits can constrain pelvis rotation and limit energy generation in the lower extremities. Shoulder pathomechanics can then develop as greater responsibility is placed on the shoulder to generate the energy lost from the proximal segments, increasing risk of upper extremity injury. Additionally, it appears that passive seated measurements of hip range of motion may not accurately reflect the dynamic range of motion of the hips through the progression of the pitch cycle.  相似文献   

卢瑟福模型中电子运动分析     

秦希峰  刘增良 《临沂师范学院学报》2007,29(3):24-26

关于卢瑟福模型中电子的运动是加速还是减速,不同文献给出不同描述,甚至是截然相反的描述.本文分别从能量和力的角度定量、定性地分析了卢瑟福模型中电子的运动情况,得出了卢瑟福模型中电子绕原子核旋转、辐射能量时作加速运动的结论.  相似文献