The effects of two different swimming training periodization on physiological parameters at various exercise intensities

This study analysed the effects of two different periodization strategies on physiological parameters at various exercise intensities in competitive swimmers. Seventeen athletes of both sexes were divided to two groups, the traditional periodization (TPG, n?=?7) and the reverse periodization group (RPG, n?=?10). Each group followed a 10-week training period based on the two different periodization strategies. Before and after training, swimming velocity (SV), energy expenditure (EE), energy cost (EC) and percentage of aerobic (%Aer) and anaerobic (%An) energy contribution to the swimming intensities corresponding to the aerobic threshold (AerT), the anaerobic threshold (AnT) and the velocity at maximal oxygen uptake (vVO₂max) were measured. Both groups increased the %An at the AerT and AnT intensity (P?≤?.05). In contrast, at the AnT intensity, EE and EC were only increased in TPG. Complementary, %Aer, %An, EE and EC at vVO₂max did not alter in both groups (P?>?.05); no changes were observed in SV in TPG and RPG at all three intensities. These results indicate that both periodization schemes confer almost analogous adaptations in specific physiological parameters in competitive swimmers. However, given the large difference in the total training volume between the two groups, it is suggested that the implementation of the reverse periodization model is an effective and time-efficient strategy to improve performance mainly for swimming events where the AnT is an important performance indicator.     

惩罚逻辑回归的击穿点

击穿点是估计未知参数稳健性的重要度量。在常规的低维逻辑回归模型中,极大似然估计的击穿点已有了广泛的研究,但少有对高维惩罚似然估计击穿点的分析。通过研究高维逻辑回归模型的惩罚似然估计的增加和替换击穿点来分析这个问题。特别地,证明惩罚极大似然估计的L₂范数总是有界的,这表明有限样本的击穿点达到了最大值0.5。此外,还提供了斜率参数的内爆击穿点的上界。模拟学习很好地支持了该理论结果。     

石油化工管道弯头冲蚀磨损数值模拟

针对油气管道运输系统存在的固液两相流对管道弯头的冲蚀破坏问题,采用CFD软件Fluent中的DPM和k-ε模型模拟多相流冲蚀现象.分析弯头内流场压力流速分布和颗粒运动轨迹,找出弯头最大冲蚀率与冲蚀位置分布规律.研究表明:在弯头内45°外侧壁面区域流场压强最大;弯头内流体流速在弯头内侧45°近壁区域达到最大值,其附近有二...     

最大匹配问题的闭环DNA算法

给出了一个解决最大匹配问题的闭环DNA算法模型,并对相应的生化实验做出了说明,实现了仅用删除实验直接构造最大匹配的构想。由于算法仅用到基本删除操作,使得算法的实现简捷、可靠。     

Direct driven wind energy conversion system based on hybrid excitation synchronous machine

A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine (HESM) is introduced in this paper. The generator is connected to an uncontrollable rectifier, and a fully controlled voltage-source inverter is used to connect the system to utility grid. An intermediate DC bus exists between the rectifier and inverter. A new control strategy is proposed which achieves the maximum power point tracking (MPPT) with the control of excitation current of HESM and stabilizes the DC link voltage with the control of inverter output current simultaneously. Specially-designed buck circuit is used to control the excitation current of HESM, and grid voltage-oriented vector control strategy is employed to realize the decoupling of the inverter output power. Simulation results and experiment in 3 kW lab prototype show an excellent static and dynamic performance of the proposed system.     

自适应雷达目标参数估计的Cramer-Rao下界

在窄带信号和窄带阵列假设下,分析了均匀面阵(UPA)自适应雷达中目标参数的最大似然估计.首先分析了UPA信号模型,随后给出了目标参数的最大似然估计和相应的CR下界.通过Jacobian矩阵给出了目标俯仰角、方位角、径向速度、模和相位的CRB.分析结果是1-D均匀线性阵列(ULA)到2-D(UPA)的推广,可用于空中运动目标参数估计的性能分析.     

Bond graph formulation of an optimal control problem for linear time invariant systems

A recent communication has proposed a conjectural procedure for representing a category of optimal control problems in bond graph language [W. Marquis-Favre, B. Chereji, D. Thomasset, S. Scavarda, Bond graph representation of an optimal control problem: the dc motor example, in: ICBGM’05 International Conference of Bond Graph Modelling and Simulation, New Orleans, USA, January 23-27, 2005, pp. 239-244]. This paper aims at providing a fundamental theory for proving the effectiveness of this procedure. The class of problem that the procedure can deal with has been extended. Its application was formerly restricted to linear time invariant siso system. The systems considered now are linear time invariant mimo systems. The optimization objective is the minimization of dissipation and input. The developments concerning the optimal control problem are based on the Pontryagin maximum principle and the proof of the effectiveness of the procedure makes a broad use of the port-Hamiltonian concept. As a result, the bond graph representation of the given optimization problem enables the analytical system, which provides the optimal solution, to be derived. The work presented in this paper is the first step in research with perspectives towards formulating dynamic optimization problems in bond graph and, towards coupling this formulation with a sizing methodology using bond graph language and a state-space inverse model approach. This sizing methodology, however, is not the topic of this paper and thus is not presented here.     

跳远运动员下肢关节振动力量训练效果的比较研究

对10名跳远专项二级运动员8周系统的振动力量训练研究表明:在刺激频率为30～35 Hz、加速度25～30m/s2条件下,实验组(I组)和对照组(Ⅱ组)髋、膝、踝关节的伸屈肌群最大功都有不同程度提高,其中I组髋关节伸屈肌、膝、踝关节的屈肌最大功增长幅度比Ⅱ组大,屈肌最大功增长幅度比伸肌大,而且屈肌的最大功要比实验前呈现显著性增长;I组髋关节伸屈肌、膝关节屈肌、踝关节伸肌相对峰力矩的增值幅度比Ⅱ组大,而髋、膝、踝三个关节屈肌相对峰力矩增长幅度相对较小.髋、膝、踝关节肌力增长情况表明:髋关节前4周增长幅度较低,后4周增长幅度较高,呈现出明显的"先低后高"变化特征;而膝、踝关节前4周增长幅度较高,后4周提高幅度降低,呈现出明显的"先高后低"变化特征.     

优秀游泳运动员陆上力量训练的准实验研究

陆上力量训练是游泳运动员力量训练的重要形式,系统的、合理的陆上力量训练会有效地增强运动员的绝对力量和爆发力水平,从而为增强水中所需的专项力量打好基础。采用单组准实验设计,以部分优秀游泳运动员为研究对象,进行为期六周的准实验研究,以探索陆上力量训练的特点,找出陆上力量科学化训练的规律,为游泳运动员的陆上力量训练提供参考。     

高原训练与铁元素研究综述

采用文献资料法,梳理了国内外高原训练期间补铁研究进行探讨和归纳,分析总结了国内外有关高原训练与铁元素主要研究热点:高原训练与铁代谢;高原训练中铁对最大摄氧量影响;高原训练中铁对运动耐力影响;高原训练中铁流失的主要原因;高原训练中补铁方式等.回顾铁元素对高原训练的影响,为健康保护与合理训练,应对从事高原训练的运动员进行血...