跳水运动视频中的运动目标分割

针对跳水运动视频中的人体运动目标分割问题,提出一种简单有效的基于颜色特征运动目标检测及分割算法。首帧进行图像预处理,利用色相和亮度两个分量加强颜色差异,然后使用OTSU算法对图像进行阈值分割。结合RGB颜色空间启发式肤色聚类结果确定运动目标所在的连通区域,最终完成首帧运动目标的自动检测。有效地克服了复杂背景变化的影响,能够快速实现跳水运动目标的分割,且对运动对象的快速整体运动有较强的鲁棒性。     

对篮球进攻基础配合战术组合与相关技术关系的研究

通过对篮球基础战术配合及它们之间相互组合的技术之间的关系进行了分析和研究,试图发现一条练与战相适应的篮球教学、训练方法和思路．     

CAD技术在四连杆机构分析与设计中的应用

为满足设计过程的参数化、可视化及设计目标的精确性要求,CAD技术广泛应用于产品的设计、开发过程。本文以四连杆机构为例,探讨CAD在其分析、设计过程中的应用。分别以数值计算软件MATLAB、二次开发编程接口VBA及操作简单的运动仿真工具Solid Works/Solid Works Motion为辅助软件,介绍其对设计过程的辅助作用。     

Whole-body predictors of wrist shot accuracy in ice hockey: a kinematic analysis

The purpose of this study was to identify joint angular kinematics that corresponds to shooting accuracy in the stationary ice hockey wrist shot. Twenty-four subjects participated in this study, each performing 10 successful shots on four shooting targets. An eight-camera infra-red motion capture system (240 Hz), along with passive reflective markers, was used to record motion of the joints, hockey stick, and puck throughout the performance of the wrist shot. A multiple regression analysis was carried out to examine whole-body kinematic variables with accuracy scores as the dependent variable. Significant accuracy predictors were identified in the lower limbs, torso and upper limbs. Interpretation of the kinematics suggests that characteristics such as a better stability of the base of support, momentum cancellation, proper trunk orientation and a more dynamic control of the lead arm throughout the wrist shot movement are presented as predictors for the accuracy outcome. These findings are substantial as they not only provide a framework for further analysis of motor control strategies using tools for accurate projection of objects, but more tangibly they may provide a comprehensive evidence-based guide to coaches and athletes for planned training to improve performance.     

质点作圆周运动时在最高点的受力分析

本文从四种情况分析了小球作圆周运动时在最高点的受力情况和运动状态．     

A design of fine motion assist equipment for disabled hand in robotic rehabilitation system

This paper reports a newly designed system intended to aid in hand rehabilitation. The motion assistance equipment consists of three parts: mechanisms for the fingers and thumb, a base of these mechanisms, and a motion assistance mechanism for the wrist. The structure of each mechanism is designed to achieve independent, fine motion assistance, especially, for the individual fingers. First, the features of each mechanism in the equipment are explained. Next, the control systems are introduced, which are constructed to realize a self-motion control strategy (i.e., the motion is controlled by its user). Using this control system, the transient response and steady state characteristics of the motion assistance mechanisms for the thumb are evaluated. Consequently, the possibility of practical application is found in regard to some improved points.     

智能监控中的运动检测算法研究

介绍了室内智能监控系统中运动检测算法的具体实现。利用帧间差分法提取运动目标,通过对差分能量和运动速度的分析判断出运动目标的大致动作。     

带电粒子自身电磁场对粒子本身的反作用

在经典电动力学的基础上,讨论了辐射阻尼力影响下非相对论性带电粒子在复合场中的运动,导出了辐射带电粒子的完整运动方程.     

Does ankle joint flexibility affect underwater kicking efficiency and three-dimensional kinematics?

ABSTRACT

Ankle flexibility is critical to obtain a high swimming velocity in undulatory underwater swimming (UUS). The present study investigated the Froude (propelling) efficiency and three-dimensional (3D) kinematics of human UUS following the extrinsic restriction of the ankle by tape application. In Experiment 1, swimmers (9 male and 8 female college swimmers) performed UUS trials involving normal swimming (Normal) and swimming with tape application at the ankle (Tape). Kicking frequency was controlled in both settings. UUS kinematics were obtained with a two-dimensional motion analysis. Swimming velocity significantly decreased during swimming with tape application compared with that during normal swimming (Normal, 1.33 m·s^?1; Tape, 1.26 m·s^?1, p < 0.05). The Froude efficiency was not affected (Normal, 0.77; Tape, 0.76), and ankle plantar angle did not decrease during swimming (Normal, 159.02°; Tape, 160.38°). In Experiment 2, lower limb rotations of a male swimmer were analysed using 3D motion analysis under the same conditions as Experiment 1. An insufficient forefoot rotation was observed during downstroke kicks (the phase of the highest acceleration to forward direction). These findings suggest that UUS velocity is affected by the mobility of end effector.     

Practical Considerations When Using Pedometers to Assess Physical Activity in Population Studies

Abstract

The aim of this study was to summarize both practical and methodological issues in using pedometers to assess physical activity in a large epidemiologic study. As part of a population-based survey of cardiovascular disease risk factors, physical activity was assessed using pedometers and activity diaries in 775 men and women ages 25–64 years who were residents of Burnie, Tasmania, 1998–99. Common data problems were classified by type. The frequency of each problem and the methods used to identify it are reported along with strategies to correct or prevent each problem type. Pedometer data from 15 (1.9%) participants could not be used due to errors in completing the pedometer protocol. Among 760 participants with usable data, the median number of steps was 9,729 for men and 10,388 for women. Pedometer steps per day were modestly correlated (r = .20, p < .0001) with the duration of pedometer wear, which ranged from 4.50 to 21.75 hr. Adjustment for wear time, however, did not alter observed correlations between pedometer steps and cardiovascular risk factors. The authors conclude that pedometers can be used in large population studies with a relatively low frequency of data errors. However, guidelines for consistent data collection and interpretation are needed.