基于多系数保角变换法的船舶垂荡纵摇运动仿真

为给航海模拟器建立实用可靠的船舶在波浪中运动的数学模型,基于二维线性势流理论,采用多系数保角变换法对每个船舶横剖面进行高精度拟合,计算各个横剖面的水动力系数和波浪激励力,利用Visual Studio自主开发出船舶在规则波中的纵向运动数值模拟程序。为验证这个数值模拟程序的可靠性,对S175集装箱船在迎浪中运动的幅值响应因子(response amplitude operator, RAO)进行数值计算。结果表明:当弗劳德数为0.275时,RAO计算结果在大部分频率范围内与试验结果吻合良好。因此,这个数值模拟程序能准确地对船舶在波浪中的运动时历进行仿真。     

基于微分方程系统的混沌控制

针对微分方程所表征的系统,对其状态方程进行了平衡点的稳定性分析。数值模拟了该系统的混沌行为,并对该系统加入棒棒控制方法进行控制。利用数值仿真分析系统的周期行为和混沌行为。通过调整适当的控制参数,将系统的混沌行为有效地控制到稳定的周期轨道。     

自由偶极子运动规律研究

讨论了由正负离子实组成的自由偶极子的相互作用能,分析了仅在该作用下偶极子的运动,求解其运动方程,得出自由偶极子的运动为匀速直线运动和简谐振动的叠加,其质心作匀速直线运动,在质心系中,两离子分别在其平衡位置附近作简谐振动.     

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

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。     

第21届冬奥会女子自由式滑雪空中技巧参赛技术动作展望

为备战2010年冬奥会,通过文献资料法和数理统计法对第17～20届冬奥会中自由式滑雪空中技巧女子决赛技术动作进行比较与分析。结果表明,获取奖牌需要掌握主流难度系数的动作组合,获取金牌需要掌握最高难度系数的动作组合,动作完成质量应达到90%以上。指出第21届冬奥会女子决赛动作组合难度系数均数还将上升,波动范围降低,为冬奥会备战工作提供参考。     

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

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.     

Tensiomyographical responses to accelerometer loads in female collegiate basketball players

The purpose of the present study was to characterise the relationship between relative versus absolute internal and external loads in collegiate basketball players throughout the course of a season. Five Division I basketball players wore triaxial accelerometers throughout the 2015–2016 season and were tensiomyographically assessed weekly. One-way repeated-measure analysis of variance (RM ANOVA) with least-significant-difference (LSD) pairwise comparisons was used to determine which absolute weekly loads were different across the season. Cohen’s d was used to supplement the determination of meaningful relative load changes. Overall RM ANOVA models suggest absolute external load differences occurred (PlayerLoad? F = 17.63; IMA? F = 31.63). Two-way RM ANOVA models revealed main effect differences were revealed between muscle groups for Tc (F = 9.11) and Dm (F = 3.25). Meaningful relative load changes between weeks were observed for both external and internal. The present study observed that tensiomyography utilised as a tool to monitor internal load may be more suitable for detecting fatigue from relative external load changes versus absolute load attained. Limiting weekly training volume changes to ≤10% may maintain appropriate adaptation. Mediolateral plane IMA? and adductor longus muscle group may be pertinent metrics when monitoring female collegiate basketball athletes.     

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

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.     

Skating start propulsion: three-dimensional kinematic analysis of elite male and female ice hockey players

The forward skating start is a fundamental skill for male and female ice hockey players. However, performance differences by athlete’s sex cannot be fully explained by physiological variables; hence, other factors such as skating technique warrant examination. Therefore, the purpose of this study was to evaluate the body movement kinematics of ice hockey skating starts between elite male and female ice hockey participants. Male (n = 9) and female (n = 10) elite ice hockey players performed five forward skating start accelerations. An 18-camera motion capture system placed on the arena ice surface captured full-body kinematics during the first seven skating start steps within 15 meters. Males’ maximum skating speeds were greater than females. Skating technique sex differences were noted: in particular, females presented ~10° lower hip abduction throughout skating stance as well as ~10° greater knee extension at initial ice stance contact, conspicuously followed by a brief cessation in knee extension at the moment of ice contact, not evident in male skaters. Further study is warranted to explain why these skating technique differences exist in relation to factors such as differences in training, equipment, performance level, and anthropometrics.     

基于数据可重用的运动估计低功耗VLSI实现

块匹配全局搜索算法(FSBM)是效果最好的运动估计算法,但是由于它庞大的运算量限制了它的应用,特别是在数字多媒体终端等对实时性和功耗要求比较高的应用场合。针对这种情况,作者提出的处理结构结合了数据重用和低功耗技术,使得该结构的功耗比传统的全局搜索结构降低50%的功耗,数据可重用性大为提高,确保了每个数据只需被读取一次,这样就确保了较少的I/O端口数和片上内存,同时实现100%的硬件资源利用率。