A biomechanical comparison of conventional classifications of bowling action-types in junior fast bowlers     

Andrew Schaefer  Rene E. D. Ferdinands  Nicholas O’Dwyer 《Journal of sports sciences》2020,38(10):1085-1095

ABSTRACT

Fast bowling is categorised into four action types: side-on, front-on, semi-open and mixed; however, little biomechanical comparison exists between action types in junior fast bowlers. This study investigated whether there are significant differences between action-type mechanics in junior fast bowlers. Three-dimensional kinematic and kinetic analyses were completed on 60 junior male fast bowlers bowling a five-over spell. Mixed-design factorial analyses of variance were used to test for differences between action-type groups across the phases of the bowling action. One kinetic difference was observed between groups, with a higher vertical ground reaction force loading rate during the front-foot contact phase in mixed and front-on compared to semi-open bowlers; no other significant group differences in joint loading occurred. Significant kinematic differences were observed between the front-on, semi-open and mixed action types during the front-foot contact phase for the elbow and trunk. Significant kinematic differences were also present for the ankle, T12-L1, elbow, trunk and pelvis during the back-foot phase. Overall, most differences in action types for junior fast bowlers occurred during the back-foot contact phase, particularly trunk rotation and T12-L1 joint angles/ranges of motion, where after similar movement patterns were utilized across groups during the front-foot contact phase.  相似文献   

创新驱动战略价值解析     

顾飞  黄睿 《重庆职业技术学院学报》2011,20(4):13-15

创新驱动战略是进一步激发我国创新的动力,是推动经济社会科学发展的核心战略：是加快产业转型升级步伐,促进战略性新兴产业发展的重要举措;是促进区域间竞争协同发展,完善现代化建设总体战略布局的内在要求：是发挥比较优势提升国家竞争力。切实保障国家安全的战略途径。迈克尔．波特首次将创新驱动作为一国取得竞争优势的重要战略予以系统地研究．认为产业发展只有从自然禀赋推动和资本推动阶段跃升到创新驱动阶段,才能使价值链从低层次跃升为高层次,只有创新驱动才是保持经济社会可持续发展的唯一有效战略途径。该文立足于创新驱动战略提出的时代背景．解析对实施和研究创新驱动战略的价值。  相似文献   

用于电力系统故障电流限制器的快速合闸开关研究     

邹积岩  董恩源  陈金祥 《上海大学学报(英文版)》2002,6(1):92-96

This paper presents a new type of fault current limiter(FCL) based on fast-closing switch,which is composed of a capacitor bank and a reactor in series.The main control component is a fast-closing switch connected in parallel with the capactitors,which is drien by the electromagnetic repulsion force.It can response the order within 1 ms.When fault occurs,the switch closes and the capacitors are bypassed.and the fault current is limited by the reactor,Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast-closing switch,it is feasible to develop the FCL with low cost and high reliability.  相似文献   

基于灰度图像的边缘检测方法   总被引：3，自引：0，他引：3  

杨群  洪春勇  刘海英 《科技广场》2005,(5):34-37

介绍了基于微分、形态学和小波变换等多种图像边缘检测的方法。在微分算子中分析了传统算子的特点和缺陷并讨论了几种具有良好边缘检测的算子。此外，还对新的边缘检测的理论和方法进行了介绍。  相似文献   

An enhanced psychoacoustic model based on the discrete wavelet packet transform     

Xing He 《Journal of The Franklin Institute》2006,343(7):738-755

The perception of acoustic information by humans is based on the detailed temporal and spectral analysis provided by the auditory processing of the received signal. The incorporation of this process in psychoacoustical computational models has contributed significantly both in the development of highly efficient audio compression schemes as well as in effective audio watermarking methods. In this paper, we present an approach based on the discrete wavelet packet transform, which closely mimics the multi-resolution properties of the human ear and also includes simultaneous and temporal auditory masking. Experimental results show that the proposed technique offers better masking capabilities and it reduces the signal-to-masking ratio when compared to related approaches, without introducing audible distortion. Those results have implications that are important both for audio compression by permitting further bit rate reduction, and for watermarking by providing greater signal space for information hiding.  相似文献   

MPEG-7可伸缩颜色描述符的研究     

李志全  黎建辉  阎保平 《中国科学院研究生院学报》2006,23(2):192-197

从最基本的概念出发，介绍了MPEG-7中的可伸缩颜色描述符出现的背景、描述符分量的语义、位平面、Haar 变换等详细情况及其匹配算法。最后，对于可伸缩颜色描述符的应用范围作了说明，这些对于将使用可伸缩颜色描述符的读者大有帮助。  相似文献   

An improved method for computing Hankel transform     

R.K. Pandey  O.P. Singh 《Journal of The Franklin Institute》2009,346(2):102-111

The purpose of this paper is to compute the Hankel transform F_n(y) of order n of a function f(x) and its inverse transform using rationalized Haar wavelets. The integrand is replaced by its wavelet decomposition. Thus representing F_n(y) as a Fourier-Bessel series with coefficients depending strongly on the local behavior of the function , thereby getting an efficient algorithm for their numerical evaluation. Numerical evaluations of test functions with known analytical Hankel transforms illustrate the proposed algorithm.  相似文献   

用于计算离散分数阶傅立叶变换的MA-CDFRFT算法改进     

陈鹏  侯朝焕  马晓川 《中国科学院研究生院学报》2007,24(2):229-234

基于中心类型DFT矩阵特征分解的MA-CDFRFT(Multiangle Centered Discrete Fractional Fourier Transform)算法在计算一组离散分数阶傅立叶变换DFRFT(Discrete Fractional Fourier Transform)时充分利用FFT运算来减小运算量。结合偶数点离散傅立叶变换DFT(Discrete Fourier Transform)运算的对称性原理，通过数学推导将MA-CDFRFT算法中的一维对称性扩展到频率和变换阶数的二维平面上。利用这个二维对称性原理，改进算法将原算法的主要计算量减小了一半左右。仿真测试结果证明了改进算法的正确性。  相似文献   

多时相AVHRR数据的傅立叶分析   总被引：10，自引：0，他引：10  

郑玉坤  庄大方 《中国科学院研究生院学报》2003,20(1):62-68

傅立叶分析(FourierAnalysis)是一种常用的信号处理方法.将中国全年 36旬的NOAA AVHRR的 1km数据采用最大值合成法获得 1 2个月的NDVI时间序列数据,然后运用离散傅立叶变换检测该时间信号的频率分布状况.结果各频率分量与NDVI的累加值及不同周期的季节性变化等生物学特征相关.其中零频率分量为均值NDVI,而 1/1 2频率分量最大程度概括了中国地表覆盖类型的全年季节性变化模式.将提取出的这些生物学特征引入到地表覆盖分类的特征空间中,提高了类别间的可分性.这些研究表明了傅立叶变换是分析多时相AVHRR数据及提取植被的生物学特征的有用工具  相似文献   

Transform domain technique for windowing the DCT and DST     

B.G. Sherlock  Y.P. Kakad 《Journal of The Franklin Institute》2002,339(1):111-120

In this paper, an algorithm is developed to apply Hann, Hamming, Blackman and related windows directly in the transform domain for the discrete cosine transform and discrete sine transform. These algorithms are useful in applications where windowing is required in order to minimize edge effects caused by implicit symmetries in the transform domain that are not replicated in the real-world data. Examples of such applications include data communication, adaptive system identification and filtering, real-time analysis of financial market data, etc. Software implementations in C language are also given.  相似文献