Ad-libitum drinking and performance during a 40-km cycling time trial in the heat

The aim of this study was to investigate if drinking ad-libitum can counteract potential negative effects of a hypohydrated start caused by fluid restriction during a 40-km time trial (TT) in the heat. Twelve trained males performed one 40-km cycling TT euhydrated (EU: no water during the TT) and two 40-km cycling TTs hypohydrated. During one hypohydrated trial no fluid was ingested (HYPO), during the other trial ad-libitum water ingestion was allowed (FLUID). Ambient temperature was 35.2 ± 0.2°C, relative humidity 51 ± 3% and airflow 7 m·s^?1. Body mass (BM) was determined at the start of the test, and before and after the TT. During the TT, power output, heart rate (HR), gastrointestinal temperature, mean skin temperature, rating of perceived exertion (RPE), thermal sensation, thermal comfort and thirst sensation were measured. Prior to the start of the TT, BM was 1.2% lower in HYPO and FLUID compared to EU. During the TT, BM loss in FLUID was lower compared to EU and HYPO (1.0 ± 0.8%, 2.7 ± 0.2% and 2.6 ± 0.3%, respectively). Hydration status had no effect on power output (EU: 223 ± 32 W, HYPO: 217 ± 39 W, FLUID: 224 ± 35 W), HR, gastrointestinal temperature, mean skin temperature, RPE, thermal sensation and thermal comfort. Thirst sensation was higher in HYPO than in EU and FLUID. It was concluded that hypohydration did not adversely affect performance during a 40-km cycling TT in the heat. Therefore, whether or not participants consumed fluid during exercise did not influence their TT performance.     

民俗体育文化旅游品牌内涵界定与品牌塑造动因分析

本文采用文献调研法、逻辑分析法等科研方法,通过对品牌、旅游品牌、民俗文化以及民俗体育文化等概念内涵的分析与界定,进而科学界定了民俗体育文化旅游品牌的概念内涵,探讨了民俗体育文化旅游品牌塑造的动因,为民俗体育旅游产业的发展指明了方向.     

基于多体动力学的发动机稳态工况动态转矩计算

理论分析发动机转矩波动产生机理,通过有限元分析得到离散化曲轴模型,建立了滑动轴承动态接触数学模型;协同各子部件间动力学关系,考虑燃气压力、变惯性力等激励载荷,在ADAMS中建立发动机曲轴连杆机构多体动力学模型,仿真计算发动机不同稳态工况下动态转矩,研究曲轴弹性、滑动轴承弹性支承、输出转速等对发动机输出动态转矩的影响。通过试验对比和简谐分析,表明了仿真方法的可行性和准确性,为车辆动力传动系统的扭振分析提供激励条件。     

应用基矢量的物质导数公式简化流体运动微分方程式的推导

推导柱坐标系及球坐标系下流体运动微分方程组通常采用的方法是根据矢量形式的运动微分方程式,利用物质导数的基本公式和正交曲线坐标系各基矢量的偏导数公式来进行,推导过程相当繁琐,尤其在教学过程中,在课堂内完成上述具体推导过程几乎是不可能的。为了寻找一种简捷的推导方法,本文依据基矢量物质导数的基本公式,计算得出了柱坐标系及球坐标系下的基矢量物质导数公式,并将它们分别应用于柱坐标系及球坐标系下的流体运动微分方程组的推导过程中。结果表明:如果将柱坐标系及球坐标系下基矢量的物质导数公式作为基本公式使用,则可以使上述坐标系下流体运动微分方程组的推导过程得到很大程度的简化。     

超临界流体萃取模型在土壤修复中的应用

针对超临界流体萃取土壤污染物的传质过程数据的缺失,分析了当前超临界流体萃取模型的优缺点,并在超临界流体萃取土壤污染物的过程是内扩散控制过程的基础之上,建立起基于微分床单元的质量守恒模型,再对模型进行求解与分析从而来模拟超临界流体萃取土壤污染物的传质过程。     

Synchronized metronome training induces changes in the kinematic properties of the golf swing

The purpose of this study was to evaluate possible effects of synchronized metronome training (SMT) on movement dynamics during golf-swing performance, as captured by kinematic analysis. A one-group, between-test design was applied on 13 male golfers (27.5 ± 4.6 years old, 12.7 ± 4.9 handicap) who completed 12 sessions of SMT over a four-week period. Pre- and post-assessments of golf swings with three different clubs (4-iron, 7-iron, and pitching wedge) were performed using a three-dimensional motion capture system. Club velocity at three different swing phases (backswing, downswing, and follow-through) was measured and cross-correlation analysis of time-series signals were made on joint couplings (wrist–elbow–shoulder) of both arms, and between joints and the club, during the full golf swing. There were significantly higher cross-correlations between joint-couplings and concomitant changes of the associated phase-shift differences, as well as reduced phase-shift variability at post-test. No significant effect of SMT was found for the club velocities. We suggest that domain-general influences of SMT on the underlying brain-based motor control strategies lead to a more coordinated movement pattern of the golf-swing performance, which may explain previous observations of significantly improved golf-shot accuracy and decreased variability after SMT.     

基于计算思维的大学计算机基础课程教学改革

计算思维是目前大学计算机基础教学研究的热点课题之一。本文结合实际教学工作,通过优化教学内容,改善教学方法,将计算思维的培养渗透到各个知识点和模块的教学中,培养学生利用计算机分析问题和解决问题的意识和能力。     

协同进化多目标优化算法在车间调度中的应用

针对车间调度问题计算复杂度较高的特点,将协同进化多目标优化算法应用于车间调度问题。计算实例结果表明,协同进化多目标优化算法应用于车间调度问题不仅可以优化效果,而且能够在一定程度上提高计算效率。     

动态环境下企业战略柔性与创新绩效关系研究

动态环境中战略柔性对企业创新绩效具有重要影响,但对其具体作用机制现有文献还缺乏深入剖析。本文从主动与被动两个角度出发,识别了前瞻型战略柔性与反应型战略柔性,在此基础上引入环境变化速度和环境变化难以预测性为调节变量,提出并验证了两种战略柔性对企业创新绩效的不同作用机制。对长三角制造业企业的实证研究表明,前瞻型与反应型战略柔性均对企业创新绩效有正向影响,但其作用效果和机制存在显著差异:总体来看,前瞻型战略柔性对企业创新绩效的效果更明显;环境变化越迅速,前瞻型战略柔性对企业创新绩效的正向作用越明显;环境变化难以预测性越高,反应型战略柔性对企业创新绩效的正向影响作用越明显。这些结论深化和拓展了战略柔性理论,也为企业的战略实践提供了有益参考。     

“三期”叠加背景下区域发展对科技创新效能响应的SD情景仿真——以陕西省为例

对2011年全国科技创新效能进行评估,认为陕西省的科技资源投入相比不小,但其科技创新效能相比全国其他省区并没有太大优势,认为其原因在于科技成果转化率不高;通过系统动力学建模原理,构建陕西经济发展的SD模型,并设定三种不同的科技成果转化率情景方案,并对选取的观测变量进行仿真,认为未来陕西省科技成果转化率需要至少提升至25%以上方能实现陕西"十二五"规划中部分约束性目标;并就如何提升陕西科技成果转化效率提出对策建议。