非稳态雾赋能网络中的在线任务卸载方法

为充分发掘分布在不同位置上的雾节点的计算资源,任务卸载被寄予众望。在雾计算场景下,以尽可能减少任务卸载的长期成本为目标,试图寻找一个高效的在线任务卸载方法。为此,这一问题被建模成一个随机规划问题,该问题中系统参数所对应的随机变量的期望会在未知时刻突变,系统参数相关信息只能在任务完成后的反馈中获得。基于非稳态多臂老虎机模型,提出一个高效的算法来解决这一具有挑战性的随机优化问题,给出理论分析证明该算法的渐进最优性。数值实验证明了该算法的优越性。     

动态雾计算网络中基于在线学习的任务卸载算法

任务卸载是雾计算的主要技术之一,即计算能力不足的节点将任务卸载给具有富余资源的节点帮助计算。以优化任务平均卸载时延和提升卸载服务成功率为目标,利用多臂老虎机理论为动态雾计算网络提出一种基于在线学习的任务卸载算法,可实时做出最优卸载决策。将该算法扩展到非稳定网络状态,使之可以动态追踪网络中节点的资源与环境变化,实时调整卸载决策。详细分析所提出算法的性能、复杂度和存储占用情况。仿真结果表明,这两种算法可达到的长期平均任务卸载时延均十分接近理想算法下的最优时延,卸载服务成功率也得到显著提升。此外,所提算法在非稳定的网络状态下能够追踪到计算资源与环境的变化。     

一种基于聚类的云计算任务调度算法

任务调度是云计算中的一个关键问题.针对 Min-Min 算法负载不平衡的缺点,引入 K-means 聚类,提出一种基于 K-means 聚类和 Min-Min 的云计算任务调度的新算法.该算法采用 K-means 聚类方法依据任务长度对任务聚类进行预处理,然后根据 Min-Min 算法的机制进行任务调度.仿真结果表明,该算法具有较好的负载均衡性和系统性能.     

Motivation counteracts fatigue-induced performance decrements in soccer passing performance

Recent theories suggest that negative effects of fatigue on performance are determined by perception of effort and motivation rather than being directly caused by reaching physiological limits. In the current experiment, the influence of motivation on fatigue-induced decrements in soccer performance was experimentally investigated. Sixty amateur soccer players performed a validated soccer-passing test before and after a fatigue protocol. Results showed that players’ motivation and performance decreased after the fatigue protocol for players in the control group. In contrast, players in the motivation group (i.e., with motivation experimentally induced after the fatigue protocol) were able to uphold their motivation and increase their performance. These results indicate that motivation plays a crucial role in performance under fatigue, as fatigue-induced decrements in soccer passing performance can be counteracted by high levels of motivation. Future research may explore the limits of this counteracting effect and extend findings to other relevant performance aspects.     

The effects of localised fatigue on upper extremity jump shot kinematics and kinetics in team handball

Team handball is a popular sport worldwide that requires numerous throws to be made throughout the course of a game. Because of the upper extremity demands of repetitive throwing, it is possible that fatigue can alter the mechanics of a shot. The purpose of this study was to determine the influence of localised fatigue on jump shot kinematics and kinetics. Eleven male team handball players (23.1 ± 3.1 years; 185.1 ± 8.3 cm; 89.7 ± 12.2 kg) volunteered. An electromagnetic tracking system was used to examine the jump shot prior to and following localised fatigue. The fatiguing protocol consisted of throwing a 2.2 kg medicine ball into a rebounder until volitional fatigue. No significant kinematic or kinetic differences were observed following fatigue. Shoulder external rotation was ?74.8 ± 14.9° prior to and ?79.0 ± 14.7° following fatigue at MER. Scapula, external rotation at ball release (BR) prior to fatigue was ?2.2 ± 7.0° and ?3.2 ± 11.1° following fatigue. Scapular internal rotation, at maximum shoulder internal rotation (MIR), changed from 18.4 ± 11.2° to 20.4 ± 11.8°. Ball velocity decreased from19.8 m · s^–1 to 18.8 m · s^–1 (P = 0.12). Accuracy percentage in the pre-fatigue trials was 60.8 ± 14.1% and 52.8 ± 12.7% following fatigue (P = 0.20). While no significant changes were observed, it is possible that other fatiguing protocols that more closely represent the aerobic and throwing demands of the sport may have a greater effect on the kinematics and kinetics of the jump shot.     

Effects of oncoming target velocities on rapid force production and accuracy of force production intensity and timing

The present study aimed to clarify the effects of oncoming target velocities on the ability of rapid force production and accuracy and variability of simultaneous control of both force production intensity and timing. Twenty male participants (age: 21.0 ± 1.4 years) performed rapid gripping with a handgrip dynamometer to coincide with the arrival of an oncoming target by using a horizontal electronic trackway. The oncoming target velocities were 4, 8, and 12 m · s^?1, which were randomly produced. The grip force required was 30% of the maximal voluntary contraction. Although the peak force (Pf) and rate of force development (RFD) increased with increasing target velocity, the value of the RFD to Pf ratio was constant across the 3 target velocities. The accuracy of both force production intensity and timing decreased at higher target velocities. Moreover, the intrapersonal variability in temporal parameters was lower in the fast target velocity condition, but constant variability in 3 target velocities was observed in force intensity parameters. These results suggest that oncoming target velocity does not intrinsically affect the ability for rapid force production. However, the oncoming target velocity affects accuracy and variability of force production intensity and timing during rapid force production.     

关于高校德育队伍建设若干问题的思考

加强高校德育工作及高校德育教师队伍的建设,把高校德育工作者引入一个新的重要机制当中,从而保证高校教师队伍的高素质。     

体育运动中抛物体问题研究的基本方法

基于抛物体运动规律对两类典型的抛物体运动（投掷项目、篮球投篮）进行了分析。在投掷项目中,投掷器械的飞行远度作为目标函数,在Excel中计算了不同的出手速度（V0）、出手角度（θ）及出手高度（H）对器械飞行远度的影响;在篮球运动中,以投篮的最小速度角和最小进篮误差作为目标函数,计算了不同的投篮距离、出手高度的情况下,投篮的最佳出手角度,寻找出篮球投篮最佳出手角的变化规律以便于运动员在实践中掌握和运用,提高投篮的命中率。     

论最后用力在掷标枪技术中的重要作用

标枪投掷中,最后用力的好坏直接影响到运动成绩,在分析了各环节的基础上提出了最后用力在标枪投掷中的重要作用。而在最后用力技术环节中,左侧支撑技术的好坏,直接影响力的传递和用力的效果,进而影响投掷成绩。     

基于任务熟人集的合同网协商策略的改进

在指出基本合同网的缺点和不足的同时,给出了一个任务熟人集的概念,提出了一种改进传统合同网协商策略的方法。