Major League Baseball pace-of-play rules and their influence on predicted muscle fatigue during simulated baseball games

Major League Baseball (MLB) has proposed rule changes to speed up baseball games. Reducing the time between pitches may impair recovery from fatigue. Fatigue is a known precursor to injury and may jeopardise joint stability. This study examined how fatigue accumulated during baseball games and how different pace of play initiatives may influence fatigue. Pitcher data were retrieved from a public database. A predictive model of muscle fatigue estimated muscle fatigue in 8 arm muscles. A self-selected pace (22.7 s), 12 s pace (Rule 8.04 from the MLB) and a 20 s rest (a pitch clock examined in the 2014 Arizona Fall League (AFL)) were examined. Significantly more muscle fatigue existed in both the AFL and Rule 8.04 conditions, when compared to the self-selected pace condition (5.01 ± 1.73%, 3.95 ± 1.20% and 3.70 ± 1.10% MVC force lost, respectively). Elevated levels of muscle fatigue are predicted in the flexor–pronator mass, which is responsible for providing elbow stability. Reduced effectiveness of the flexor–pronator mass may reduce the active contributions to joint rotational stiffness, increasing strain on the ulnar collateral ligament (UCL) and possibly increasing injury risk.     

基于细观结构有限元模型的环氧沥青混合料间接拉伸试验研究

运用有限元方法建立环氧沥青混合料细观结构模型,对其间接拉伸试验(IDT)进行数值模拟.首先借助图像处理技术得到由集料和沥青砂浆组成的环氧沥青混合料二相细观结构,并通过蠕变试验获取沥青砂浆常温下的黏弹性材料参数,最后结合有限元手段建立包含集料、砂浆等在内的混合料细观结构有限元模型.数值模拟结果表明,有限元计算的混合料劲度...     

审美人类学理论活力与张力的呈现——评向丽的《审美制度问题研究》

审美制度既是审美人类学学科理论体系中的一个重要概念和中心议题,也是人类社会审美和艺术生存机制的集体表征。《审美制度问题研究》以其严谨的学理分析和介入现实的学术品质探讨了＂美＂是如何被建构和能被建构的文化生存机制,随着审美制度的深入研究,审美人类学理论的活力与张力将会得到更好的呈现。     

认知与情绪在音乐中的联系

认知与情绪在音乐上联系紧密。文章用音乐张力的概念联结音乐结构的认知与音乐情绪。期待和声音事件之间的相互作用被假定在产生音乐的紧张和放松方面和音乐情绪中发挥着重要的作用。知觉的研究支持了音乐结构引起听者期望的音乐理论的描述。音乐张力与音乐的结构、音乐的形式有联系。音乐情绪随时间在强度和质量上改变,而且这些情绪在心理生理学测量上也发生变化。     

血腥、金钱、紧张——试评余华《兄弟》中的暴力叙事

暴力一直是余华小说思考和表现的主题。暴力话语带来了作家和现实的紧张关系。不同的文本体现出了对处理紧张感的态度和方式。新作《兄弟》延续了余华的暴力叙事。作家在上下部中分别阐释了两种暴力:"文革"的血腥硬暴力和现代的金钱软暴力。对于硬暴力,余华在文本中通过家庭温情和幽默的方式来缓解紧张感。但对于后者作者只能不停地展示,没能找到缓解的方式。     

HDPE抗渗膜在高温天气下的施工工艺

HDPE抗渗膜作为防渗型土工合成材料,由于其抗拉强度高、防渗性能好、施工方便等特点,广泛应用于垃圾填埋场、污水处理厂、化工厂区的防渗加固中。结合工程实例,介绍HDPE防渗膜在石油化工钢储罐工程中的应用。     

拱桥柔性吊索索力振动频率法测试

通过对拉索索力振动法测试计算公式简化分析,引入振动法测试的索力系数,只要在桥梁施工过程中通过压力传感器法或张拉千斤顶法确定各条吊索的索力系数,则振动频率法测试索力的公式变成了仅与拉索振动频率有关,对提高利用振动频率法测索力精度意义很大,尤其是精确测试短索的索力。     

Modified surface tension model for free surface flow with single-phase lattice Boltzmann method

A single-phase lattice Boltzmann model with modified surface tension is developed in this paper to solve the problem of high-density-ratio free surface flow.The computational efficiency and accuracy are both enhanced.The restriction to the relaxation factor （which needs to be smaller than 1） is circumvented by the new surface tension algebra,due to its rational physical nature compared with the treatment of Xing,Buther and Yang in their paper （Comp.Mater.Sci.,2007,39（2）：282-290）.The proposed stable surface tension scheme is applied to simulate the free deformation of a square droplet with surface tension effect and the process of a droplet impinging on a liquid film.The numerical solution for free deformation of a droplet agrees well with thermodynamic principles,and also achieves high accuracy in comparison with Xing,et al.＇s model.Three typical impinging modes are successfully obtained with the new scheme,and another particular mode found by Wang and Chen is also successfully simulated.The evolutions of liquid crown agree well with the power law related to time.     

霍尔式肌张力换能器原理与医学物理实验设计

采用线性霍尔电路和永磁体,基于悬臂梁弹性体系统,研制了一种霍尔式肌张力换能器。2个线性霍尔电路以永磁体为对称中心,构成对称互补取样电路,以差分方式输出信号电压;张力使悬臂梁发生弹性形变,携带磁体产生位移并引起磁场变化,应用霍尔效应实现了肌张力与信号电压的线性变换。取样系统的对称互补式设计,抵消了非线性变量对测量的影响,换能器具有高线性度指标;差分式输出能够抑制共模干扰和零点漂移,并增大了信号幅度;非接触式的测量方法,提高了换能器的可靠性。新型换能器应用于医学物理实验,灵敏度高、抗干扰能力强,实验效果优于应变式换能器。     

最大气泡法测溶液表面张力实验数据处理的改良

为了改进最大气泡法测正丁醇溶液表面张力实验的数据处理,用希什科夫斯基模型拟合了σ—c关系曲线,拟合效果较好,拟合后的处理步骤简便,并用外推法确定正丁醇分子横截面积,结果更准确。