Perform kicking with or without jumping: joint coordination and kinetic differences between Taekwondo back kicks and jumping back kicks

We investigated joint coordination differences between Taekwondo back kicks and jumping back kicks, and how jumping (in performing the latter) would alter engaging ground reaction forces (GRF) in executing kicking. Ten skilful athletes volunteered to perform both kinds of kicking within the shortest time for three successful trials. Three high-speed cameras and two force platforms were used for data collection, and the trial with the shortest execution time was selected for analysis. Movements were divided into the rotation and attack phases. With comparable execution time and maximum joint linear/angular speeds, back kicks and jumping back kicks differ mainly in larger GRF in the latter, and in greater target acceleration in the former probably because the support leg prevented athletes’ rebounding after impact. In addition, more prominent antiphase and in-phase coordination between the shoulder segment and knee joint, and elongated rotation phase were found in jumping back kicks. Larger GRF values in jumping back kicks were generated for jump take-off rather than for a more powerful attack. In back kicks although the support leg remained ground contact, greatly decreased GRF in the attack phase suggested that the support leg mainly served as a rotation axis.     

基于VB的多轴运动控制系统的软件开发与应用

为了满足多轴运动控制系统高效、高精度的控制要求,采用基于数字信号处理器（DSP）技术加上一个现场可编辑门阵列（FPGA）的运动控制器,搭建了多轴运动控制系统的实验平台。并利用VB软件编写了多轴运动系统的控制程序。结果表明,生成的控制界面可以对系统进行方便、灵活的运动控制。     

考虑遮挡的视频车辆跟踪

为了对遮挡情况下的运动车辆进行跟踪,提出一种基于分块的车辆跟踪算法。该算法将目标车辆以可重叠的方式划分为若干大小一致的子块。在分块的基础上估计所有子块的运动矢量,检测噪声运动矢量并进行调整,以减少运动矢量估计的误差,然后对子块进行移位以实现车辆跟踪。为了处理车辆间的遮挡现象建立了马尔可夫随机场描述子块之间的关系,利用欧氏距离定义块的邻域,并基于块的直方图构建能量函数,最后利用模拟退火法对能量函数进行优化,以对遮挡区域进行分割。实验结果表明,该算法能够对遮挡车辆进行准确跟踪。     

图文编排在设计中的作用

编排文字和图形是一门艺术,这门艺术有着悠久的历史,是人类文化的重要遗产,是提高作品的欣赏度的重要环节,能够直接影响到作品的销量、价值评估等。可以说,图形和文字设计是提高作品的诉求力,赋予版面审美价值的一种重要构成技术。由此说来,图文的编排工作也可以说成是艺术创作种类的一种,它是根据人的审美学角度合理的将图片文字编排成一种让人感觉最舒适的模式,以最好的角度来传达作品的核心思想。图形和文字永远是视觉设计的两大重要设计元素。     

分数跳－扩散模型的标准回望期权定价

文章以看涨期权为例探讨了分数跳－扩散模型的标准回望期权定价问题,其中 H∈（12,1）,并给出了定价公式。     

Natural surface design for sliding mode control with multiple discontinuous inputs

It is well known that sliding mode control is based on the definition of an invariant manifold, where the system dynamics are forced to in a finite time. Such a manifold is somewhat arbitrarily defined, as long as the system dynamics are stable on it. Computational and control effort may vary depending on selected manifold. Obviously, if a system has naturally acceptable stable dynamics around a desired equilibrium point, no control is needed unless uncertainties or disturbances are present. It would be desirable that if such a system had uncertainties or disturbances, the control effort be designed only to overcome the effect of such factors. For a system with first order dynamics and affine control input, designing a sliding mode control overcoming only such uncertainties or disturbances is a trivial task. When a higher order dynamics system is involved, unit control may be used, where the input control signals are not discontinuous, but when only discontinuous control inputs are available, a design approach is not readily available. In this paper, taking advantage of the natural stable dynamics of a system, a sliding mode control approach is introduced for designing multiple discontinuous control inputs, where the control effort overcomes only uncertainties, disturbances or unstable dynamics. Two illustrative examples are given in order to show the feasibility of the method.     

动态分层二值进化全关节驱动跟踪贫化算法

在人体运动跟踪建模中,需要对样本集的多样性特征进行贫化处理,以提高全关节驱动模式运动状态跟踪的准确性。传统方法采用量子进化和粒子滤波算法进行人体运动跟踪贫化算法实现,算法在全关节多样化样本特征运动模式下,跟踪效果不好。提出一种采用动态分层二值进化处理的改进的量子进化粒子滤波全关节驱动模式跟踪方法,解决多样本特征的贫化问题。进行人体全关节驱动模式动力学分析及人体运动跟踪模型构建,通过动态分层处理技术,获得二值前景图像,求得人体关节的全方位信息特征,通过动态分层二值进化方法,准确地找到各关节位置,构建亮度模型函数,实现贫化处理。实验表明,改进算法能实现对体操运动员运动幅度大的肘、腕、踝部位均得到了准确的跟踪结果,贫化效果较好,运动状态估计精度较高。     

摇杆滑块机构滑块匀速运动时各铰链运动状态分析与仿真

文章以摇杆滑块机构滑块沿任意曲线做匀速运动为目标,首先建立相应的矢量方程式并进行求解,接着又用Pro/E软件建立简单骨架模型进行仿真分析,研究方法及获得结果为进一步研究机构铰链处驱动电机的控制方法提供了一定的依据。     

平面与空间的转化，变与不变的升华--立体几何翻折问题探究

翻折问题是立体几何的重要问题,是平面几何与空间几何问题转化的集中体现。翻折问题的探究必须充分利用不变量和不变关系,抓住翻折前后始终位于折线同侧的几何量和位置关系保持不变。     

我国优秀跳高运动员技术动作诊断研究

研究选取2010年全国田径锦标赛跳高比赛前六名运动员作为研究对象,使用三维高速摄像机对助跑阶段最后两步进行全程拍摄,使用APAS软件对数据进行定量分析。通过对中国顶尖跳高运动员起跳阶段的步长、摆动腿蹬伸膝角、起跳腿离地水平速度等技术指标进行生物力学分析。结合国内外学者对跳高运动员起跳阶段技术分析的研究成果与跳高运动的技术特点和发展趋势,为中国跳高运动员训练提出合理化建议。