Effects of oncoming target velocities on rapid force production and accuracy of force production intensity and timing

The present study aimed to clarify the effects of oncoming target velocities on the ability of rapid force production and accuracy and variability of simultaneous control of both force production intensity and timing. Twenty male participants (age: 21.0 ± 1.4 years) performed rapid gripping with a handgrip dynamometer to coincide with the arrival of an oncoming target by using a horizontal electronic trackway. The oncoming target velocities were 4, 8, and 12 m · s^?1, which were randomly produced. The grip force required was 30% of the maximal voluntary contraction. Although the peak force (Pf) and rate of force development (RFD) increased with increasing target velocity, the value of the RFD to Pf ratio was constant across the 3 target velocities. The accuracy of both force production intensity and timing decreased at higher target velocities. Moreover, the intrapersonal variability in temporal parameters was lower in the fast target velocity condition, but constant variability in 3 target velocities was observed in force intensity parameters. These results suggest that oncoming target velocity does not intrinsically affect the ability for rapid force production. However, the oncoming target velocity affects accuracy and variability of force production intensity and timing during rapid force production.     

择时营养补充方法在优秀自行车运动员营养调控中的应用

目的:为了研究择时营养补充对自行车运动员运动能力的影响和择时营养补充方法在自行车运动员营养调控中的应用,为运动时间营养学理论提供实验依据.方法:对8名优秀自行车运动员在珠海和深圳训练周期内的营养调控进行研究,测试部分血生化指标和心肺功能以及运动现场测试运动能力.结果:本实验发现,运动员在训练期间进行择时营养补充,男子血清总睾水平增加了9.22%(P＜0.05);血清CK水平下降40.61%(P＜0,05);动态追踪Hb、血糖和血胰岛素水平的变化,在训练周期内,Hb呈下降趋势,但仍能维持在较高水平,训练前后比较下降了9.74%(P＜0.05),而血糖浓度和胰岛素水平的波动均在正常范围.结论:以择时营养补充方法应用于优秀自行车运动员训练期间的营养调控,并遵循"择时补充、联合补充、个体化补充和交替刺激"的原则,可提高运动员体能和促进体能恢复,对调节内分泌功能、促进运动后骨骼肌机能的快速恢复有积极作用.     

大学生健康运动新模式

从增质到健身,从显性到隐性课程开发的教改实践中研究我国高校体育向着健康转移的思路、理念及其发展方向;探索改变校园体育文化与运动的成份、内核及其价值取向;创新发展健康运动的育人目标、序列及其模式,把充满生机、适应校园环境、满足体育需求的健康运动推向教学改革的繁荣市场。     

我国优秀游泳运动员出发技术辅助训练的研究

为改进我国优秀游泳运动员的出发技术,采用观测和实验方法,通过拍摄运动员陆上和水下出发技术录像以及出发计时,对出发技术进行运动生物力学诊断和分析。在此基础上,根据运动员自身特点和不同泳姿提出相应的入水启动方式,并研制出发训练辅助器材,对出发预备姿势、腾起角度以及飞行远度和入水角进行控制。实践证明:这是一种快捷、有效的出发技术辅助训练方法。     

一个Cauchy数列的构造

本文在一个二阶连续可微的实值函数的单重零点的邻域内,构造了一个数列,并证明了它收敛于该单重零点.     

船位信息的甚高频传输系统

对船位信息的甚高频无线传输系统的基本构成和实现原理进行了研究，并讨论了有关信息传输中的抗干扰问题。     

《周易》“六十四卦图”解(下)

通过论证"龟甲九宫"与"八卦图"组成"九宫八卦图",进而揭示出"八卦相重(八乘八)成六十四卦"的生成原理,纠正了《易》学界流传至今的宋代邵雍、朱熹所谓"八卦变十六卦变三十二卦变六十四卦"错误理论。     

Braided composite materials for the production of lightweight, high rigidity golf shafts

Braiding is not currently used in the production of golf shafts. The objective of this work was to develop, through a modelling process consisting of altering lamina sequence, a golf shaft, using braided laminas, which would have mass, stiffness and torque comparable to commercially available composite and steel shafts. A 2D conical braided composite model was previously developed and validated to predict elastic constants of braided closed meshed structures. Energy methods were used to calculate the stiffness and torque of shafts using prescribed industry approaches. Shaft mass was calculated based on geometry and density of constitutent materials. Modelled shafts had both braided and unidirectional layers and compared favourably with or were better than commercially available composite and steel shafts in terms of deflection force and twist angle; they had the same weight as composite shafts but were much lighter than steel shafts. If these findings are verified, braided composites would be a viable and effective approach to the design of future golf shafts.     

电力系统机电暂态-电磁暂态混合仿真的研究

随着电网规模的日趋扩大,传统的机电暂态或者电磁暂态仿真软件在分析电网的运行特性时,已开始显露出各自的局限性。将两者联合起来进行混合仿真,可以较好的解决仿真的规模、速度和精度的协调问题。在分析机电暂态和电磁暂态各自的特点的基础上,文中介绍了两者接口的原理和所涉及的问题。最后,对现有的三种混合仿真的接口时序方法进行了对比分析。     

高阶Voronoi图在超市选址定位研究中的应用

以石家庄市桥东区为例,选取该地区的七家大型综合超市进行大量实际调查和科学的分析研究,根据各种影响因素构建超市位置和市场面积类型的研究模型,采用高阶Voronoi图对该地区内超市的势力范围进行研究,指出新超市选址的大概轮廓,并根据加权因素给出最佳选址范围和新建超市的规模.