The fourth dimension: A motoric perspective on the anxiety–performance relationship

This article focuses on raising concern that anxiety–performance relationship theory has insufficiently catered for motoric issues during, primarily, closed and self-paced skill execution (e.g., long jump and javelin throw). Following a review of current theory, we address the under-consideration of motoric issues by extending the three-dimensional model put forward by Cheng, Hardy, and Markland (2009) (‘Toward a three-dimensional conceptualization of performance anxiety: Rationale and initial measurement development, Psychology of Sport and Exercise, 10, 271–278). This fourth dimension, termed skill establishment, comprises the level and consistency of movement automaticity together with a performer's confidence in this specific process, as providing a degree of robustness against negative anxiety effects. To exemplify this motoric influence, we then offer insight regarding current theories’ misrepresentation that a self-focus of attention toward an already well-learned skill always leads to a negative performance effect. In doing so, we draw upon applied literature to distinguish between positive and negative self-foci and suggest that on what and how a performer directs their attention is crucial to the interaction with skill establishment and, therefore, performance. Finally, implications for skill acquisition research are provided. Accordingly, we suggest a positive potential flow from applied/translational to fundamental/theory-generating research in sport which can serve to freshen and usefully redirect investigation into this long-considered but still insufficiently understood concept.     

区间时变细胞神经网络周期解的鲁棒指数稳定性

本文研究一类区间时变扰动神经网络系统周期解的鲁棒指数稳定性.获得了一系列关于鲁棒指数稳定性的判据.     

需求不确定情况下沿海燃料油供应鲁棒优化

针对沿海地区燃料油供应问题,制定燃料油配送方案,设计配送航线和配送量使运输成本和库存成本最小,同时考虑需求不确定的情况,使需求发生一定变动时原方案依旧可行。与不考虑需求不确定的供应方案相比,使用鲁棒优化方法得到的结果可靠性更强,发生缺货的可能更小。由于需求不确定情况下存在的二次约束严重影响模型的求解效率,提出一种两阶段求解方法来分解问题,使求解效率得到明显提高。对于存在需求不确定情况的供应系统,决策者使用该鲁棒优化模型时,可以根据风险偏好并通过调整参数最大限度地提高供应方案的可靠性。     

Cutting your losses: Could best-practice pedagogy involve acknowledging that even robust hope may be vain?

A recent special issue of Asia-Pacific Journal of Teacher Education (Vol. 35, Issue 3, 2007) championed ‘robust hope’ as fundamental to achieving educational utopias, and yet key features of hope were largely overlooked. Although hope feels good and has utility in some circumstances, in other situations different motivations – positive (e.g. curiosity) or negative (e.g. frustration) – may offer greater pedagogical value. Given its intrinsic uncertainty, robust hope is often indistinguishable from vain hope (before the fact). Hence, robust hope may lead to: (1) failure; (2) an exacerbation of existing judgement biases; and (3) emotional reasoning. Given these attendant risks, best-practice principles require that the net pedagogical impact of robust hope be assessed. Occasionally, cutting one's losses is rational – not cynical or apathetic, as suggested by earlier contributors. Positioning robust hope as ‘realistic risk taking’ does not resolve the aforementioned problems. In the end, a combination of motivations (possibly, although not necessarily, including hope) will likely provide the best pedagogical outcomes.     

运量变化下的干散货海河集散优化

为降低海河集散运输的总运输成本,根据对三程运输、江海直达运输和减载运输特点的评价,研究干散货海河集散的优化问题.在成本最低基础上,考虑运量变化对干散货海河集散的影响.从大型制造企业和船运公司的角度构建一个运量变化的干散货海河集散模型.以铁矿石内河运输为例,将鲁棒优化模型与普通模型进行对比.结果表明,虽然鲁棒优化模型使得成本小幅度提高,但可以有效地控制运量变化对运输网络的影响,使得优化后的模型能够处理有一定变化幅度的运量.     

Robust Adaptive Control Design for Rotorcraft Unmanned Aerial Vehicles Based on Sliding Mode Approach

This paper presents a nonlinear robust control design method for a generic rotorcraft unmanned aerial vehicle（RUAV）. The control objective is to let the RUAV track some pre-defined time-varying position and headingtrajectories. The proposed controller employs feedback linearization process to realize the dynamic decoupling controland applies adaptive sliding mode control to compensate for the parametric uncertainties and external disturbances.The global asymptotical stability is proved via stability analysis. Compared with the cascaded controller, the proposedcontroller demonstrates a superior tracking performance and robustness through numerical simulation in the presenceof parametric uncertainties and unknown disturbances.     

稳健统计方法在开放大学考试分析中的实验研究

开放大学的终结性考试成绩数据中异常值存在的概率较大,为考试成绩的统计分析带来一定困难。稳健统计方法对考试成绩数据异常值的处理较为科学。实验研究表明,当考试成绩中存在极高分、极低分、缺考等情况时,稳健统计的统计结果受其影响较小,从而能够更准确、客观地反映学生学习的整体水平。     

不确定广义系统的鲁棒容错控制

对一类具有范数有界参数不确定性广义系统,运用矩阵不等式方法,提出了一种鲁棒容错反馈设计方法.利用该方法设计的闭环系统,不仅针对执行器发生故障时具有完整性,而且对所有容许的参数不确定性具有鲁棒性.     

健美操练习对女生体形及心肺功能的影响

通过对60名18～20岁女大学生每周参加不同强度的健美操锻炼后，身体形态和心肺功能指标的测试，表明一定(不同)强度的健美操训练对提高女生身体素质、改善心肺功能、促进身体形态的发育有良好的作用。     

Evaluation of a New Mean Scaled and Moment Adjusted Test Statistic for SEM

Recently a new mean scaled and skewness adjusted test statistic was developed for evaluating structural equation models in small samples and with potentially nonnormal data, but this statistic has received only limited evaluation. The performance of this statistic is compared to normal theory maximum likelihood and 2 well-known robust test statistics. A modification to the Satorra–Bentler scaled statistic is developed for the condition that sample size is smaller than degrees of freedom. The behavior of the 4 test statistics is evaluated with a Monte Carlo confirmatory factor analysis study that varies 7 sample sizes and 3 distributional conditions obtained using Headrick's fifth-order transformation to nonnormality. The new statistic performs badly in most conditions except under the normal distribution. The goodness-of-fit χ² test based on maximum-likelihood estimation performed well under normal distributions as well as under a condition of asymptotic robustness. The Satorra–Bentler scaled test statistic performed best overall, whereas the mean scaled and variance adjusted test statistic outperformed the others at small and moderate sample sizes under certain distributional conditions.