流媒体中一种高质量视频内容的设计     

陈敬远 《浙江传媒学院学报》2004,11(2):33-36

结合当前流行的流媒体技术,深入分析了流媒体技术及其文件格式,讨论了如何实现流媒体高质量的视频内容.在此基础上,本文实现了一个基于流媒体的高质量视频内容的设计.  相似文献   

Sport disciplines,types of sports,and waist circumference in young adulthood – a population-based twin study     

Mirva Rottensteiner  Sara Mäkelä  Leonie H. Bogl  Timo Törmäkangas  Jaakko Kaprio  Urho M. Kujala 《European Journal of Sport Science》2017,17(9):1184-1193

Purpose: The benefits of physical activity (PA) in preventing abdominal obesity are well recognized, but the role of different sport disciplines remains open. We aimed, therefore, to investigate how participation in different sport disciplines, and the number and types of sports engaged in are associated with waist circumference (WC) in young adulthood. Methods: This population-based cohort study comprised 4027 Finnish twin individuals (1874 men), with a mean age of 34 y (32–37), who answered a survey, including self-measured WC. We extracted the number and identified the types (aerobic, power, and mixed) of the different sport disciplines respondents reported participating in. Results: The number of sport disciplines participated in was inversely associated with WC, the linear decrease averaging 1.38?cm (95% CI 1.10–1.65) per each additional sport discipline. The result persisted after adjustment for the main covariates, such as volume of PA and diet quality. Among dizygotic twin pairs discordant for sports participation (0–2 vs. 5 or more disciplines), the mean within-pair difference in WC was 4.8?cm (95% CI 0.4–9.1) for men and 11.2?cm (95% CI 4.4–18.0) for women; among discordant monozygotic pairs, no differences were observed. In men, all three types of sports were individually associated with smaller WC, while in women, only mixed and power sports showed this association. Conclusions: Participation in several sport disciplines and sport types was associated with smaller WC among young adults in their mid-30s. Shared genetic background may explain some of the associations.  相似文献   

乒乓球运动员以预防损伤为主的功能训练          下载免费PDF全文

李男  叶晶龙 《体育科研》2019,(5):95-98

功能训练的理念来源于康复领域，现已逐步应用到运动训练中。由于乒乓球运动的项目特征，乒乓球运动员肩关节、腰椎关节、膝关节、踝关节、腕关节等部位容易出现运动损伤。通过对乒乓球运动员常出现的功能问题进行分析，寻找存在的常见问题，进而提出相应的功能训练建议。乒乓球运动员可根据情况，增加改善肩关节、胸椎关节、髋关节、踝关节的活动范围的训练，提高肩胛骨、核心和下肢稳定性的训练，以及改善肩袖、躯干肌力不平衡的训练，通过针对性的功能训练有效减少乒乓球运动员损伤的发生。  相似文献   

Optimal sampling frequency in recording of resistance training exercises     

Paolo Bardella  Irene Carrasquilla García  Marco Pozzo  Julio Tous-Fajardo  Eduardo Saez de Villareal 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):102-114

The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f_99.9 = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality.  相似文献   

实轴增量式光电编码器测量电路的设计   总被引：1，自引：0，他引：1  

李劲松 《实验室研究与探索》2007,26(2):12-15

介绍了如何设计增量式光电编码器的输出信号处理电路,并从该电路设计的四个方面着手,较为详细地阐述了电路组成的构思、设计及实现过程。  相似文献   

一种双旋翼控制系统的建模与仿真     

鲁兴举  彭学锋  郑志强 《实验室研究与探索》2007,26(7):27-30,42

对一种复杂的多输入多输出控制系统—双旋翼系统进行了研究。在详细、准确地进行运动学和动力学分析的基础上,建立了比较完备的双旋翼系统数学模型,并对双旋翼控制系统的姿态控制进行了初步仿真,并给出了仿真结论。  相似文献   

单板剪切机数控系统的设计     

钟学俊  高玉萍 《德州学院学报》2011,27(4):83-85

根据木工单板剪切机工作的特点,研制了一种基于旋转编码器和单片机控制的单板剪切机数控系统,主要由绝对位置测量系统、单片机控制系统、剪切系统和单板夹持系统四部分组成,可以通过设置剪切参数,方便调节剪切长度,最大程度避免浪费,提高工效.  相似文献   

适应社会稳定工作的需要深化高校"两课"教学改革的探索和实践     

江洪明 《河池学院学报》2003,23(3):71-74

本文分析了21世纪我国高校"两课"教学所面临的新挑战,比较系统地总结了为适应新世纪社会稳定工作的需要,深化"两课"教学改革的一些实践经验,在教学改革的指导思想、教学原则上以及在教学观念、教学内容、教学方法、教学手段、教学环节、教学管理体制等方面的改革上进行了有益的探索.  相似文献   

基于代数分解的MSI组合电路扩展技术     

曹天汉 《科技通报》1996,12(5):279-284

讨论了一位全加器及优编器的逻辑功能，给出了适当的代数表示形式，在此基础上提出了基于代数分解方法的扩展技术。  相似文献   

城市表层土壤重金属污染分析     

梁玉兰 《山西广播电视大学学报》2015,(1):103-106

通过某城市土壤地质环境采集的319个取样点,分析所得到的砷(As)、镍(Ni)、铅(Pb)、汞(Hg)、铜(cu)、锌(Zn)、铬(Cr)、镉(Cd)等在城市土壤中主要重金属元素的浓度,与实际相结合,利用样点的数据,借助Matlab数学软件中mesh函数绘制出三维模型,一个取样地样分区图,八个八种重金属元素浓度分布图,九个俯视图,对问题所做工作进行评价,总结优缺点,对城市环境的演变模式研究给出展望。  相似文献