弹性力学习题一题多解的探讨     

陈敏 《金陵科技学院学报(社会科学版)》1999,(1)

本文通过灵活运用弹性理论知识解题，达到巩固知识、培养分析问题和解决问题的能力。  相似文献   

中国乒乓球队制胜因素的实证研究   总被引：1，自引：0，他引：1  

方文 《广州体育学院学报》2007,27(3):6-9

中国乒乓球队之所以能够长胜不衰,雄踞世界乒坛,是与多年来乒乓球队技战术的精彩演绎及强有力的后备人才培养分不开的。中国乒乓球队制胜因素即“三件宝”是指技术组合的多样化、击球点的全面性以及反方向技术的应用能力,这三个方面对取得比赛的胜利起着关键的作用。主要通过观察法和数理统计法对这"三件宝"在优秀运动员比赛过程中的应用情况进行了研究,力求发现其中的规律,为运动员今后的训练提供参考依据。  相似文献   

基于TVCSE拟合的网络入侵预测方法     

牛爱民 《科技通报》2015,(6)

针对传统算法网络入侵预测中,网络检测数据相关性不强,大规模网络入侵导致预测准确性不高的问题。提出了一种基于时序变化率曲面极值(Time-series variation curved surface extremum:TVC-SE)拟合的网络入侵预测算法。对网络流量信息数据进行实时获取,以时序为时间度量构建变化率曲面模型;分别对时序变化率曲面模型的局部极值进行迭代计算,将共有的局部极值作为最终的预测极值进行存储,同时以该时刻的协同局部极值为参考,提高了网络入侵预测的准确性。仿真实验表明,该测试方法能够达到较高的测量精度,虚警率比传统算法平均降低了12.4%,预测时间减少在2.5 s左右,在不增加成本,符合网络程序计算复杂度的情况下,满足了网络入侵预测的要求。  相似文献   

Effects of changing speed on knee and ankle joint load during walking and running     

Ana Cristina de David  Felipe Pivetta Carpes  Darren Stefanyshyn 《Journal of sports sciences》2015,33(4):391-397

Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s^?1 ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes.  相似文献   

约化弦EKR理论背景方程的二重逆散射方法     

张春红  张忠政  谢立云 《安顺学院学报》2011,(3):121-123,131

文章首先构造了约化弦EKR理论背景方程的二重形式,然后给出了适合于该理论的二重逆散射方法,并利用此方法求取了该理论的二重孤子解族。  相似文献   

基于Sobel算子和混合有理插值的图像压缩方法     

陈宝国  李宁 《廊坊师范学院学报(自然科学版)》2011,11(4)

为提高图像的压缩效率,提出一种基于Sobel算子和非线性混合有理插值的图像压缩方法。将Sobel算子应用于图像的轮廓提取,利用二元Newton．Thiele型向量连分式建立有理插值曲面,然后对插值函数进行重采样,按要求实现图像压缩。实验结果表明,该方法能有效应用于数字图像的压缩处理,具有计算简单、易于编程实现等优点,是一种较实用的方法。  相似文献   

反三角函数是怎样产生的？     

衡阳  聂学建 《职大学报》2014,(2):71-72

三角函数学了正弦、余弦和正切,没学余切、正割和余割;更没学反三角函数了!这就是今年某些大专新生在初等数学方面的薄弱之处;读懂本文后,新生们一定能有所弥补,在进校后的高等数学学习中扎实地迈进一大步。  相似文献   

Lower extremity power during the squat jump with various barbell loads     

Daniel Jandacka  Jaroslav Uchytil  Roman Farana  David Zahradnik  Joseph Hamill 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(1):75-86

The purpose of this study was twofold: (1) to determine the barbell load that maximised the system power as well as the ankle, knee, and hip joint powers during the squat jump, and (2) to compare the system powers computed from two different methods: the centre of mass (COM) method and the barbell method. Seven male throwers were recruited in this study. The system power (COM method) and the ankle, knee, and hip joint powers were determined with the load incrementally set at 0%, 10%, 30%, 50%, 70%, and 90% of one repetition maximum. The largest system power was observed at the load of 30% (p < 0.008) while the largest ankle and knee powers were observed at 70% and 0% (p < 0.05). The barbell method overestimated the system power (p < 0.001) when compared to the COM method. It was concluded that the barbell method could influence load optimisation in squat jump. The optimal barbell load which maximised the system power did not maximise the ankle, knee, or hip power simultaneously.  相似文献   

Comparison of support leg kinetics between side-step and cross-step cutting techniques     

Yuta Suzuki  Michiyoshi Ae  Shunsuke Takenaka  Norihisa Fujii 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(2):144-153

The purpose of this study was to investigate differences in the support leg joint moment and moment power between side-step (SS) and cross-step (CS) cutting techniques with a prescribed 90° cutting angle. Ground reaction forces (1,000 Hz) and three-dimensional kinematics (250 Hz) of SS and CS cutting techniques were collected from 20 male college athletes. Normalised peak knee extension moment was larger in the SS technique than in the CS technique (0.40 ± 0.10 in SS; 0.26 ± 0.08 in CS). In the SS technique, the knee extensors ( ? 0.10 ± 0.06 in SS; ? 0.02 ± 0.04 in CS) and ankle plantarflexors ( ? 0.12 ± 0.05 in SS; ? 0.07 ± 0.03 in CS) did significantly more negative work (normalised). The direction change angle (40.5 ± 8.7° in SS; 33.0 ± 6.8° in CS) and the decrease in horizontal velocity of the centre of mass ( ? 0.63 ± 0.23 m/s in SS; ? 0.31 ± 0.23 m/s in CS) were significantly larger in the SS technique. These results suggest that the SS technique is an effective means of changing running direction at the expense of velocity of the centre of mass and that the CS technique is better for minimising the reduction in horizontal velocity of the centre of mass.  相似文献   

半线性椭圆型偏微分方程反问题解的整体惟一性     

赵凯宏 《玉溪师范学院学报》2006,22(9):65-72

研究了半线性椭圆型偏微分方程-Δu+B.gradu+a(x,u)=0u|Ω=g∈W2-1/p,p(Ω)的反问题的解的整体惟一性.证明过程中应用了线性化方法和Dirichlet——Neumann映射.  相似文献