三相电动机绕组接错与嵌反时的检查和首末端的判别

针对三相电动机绕组接错与嵌反故障的检查和绕组首末端的判别,论述了故障类型,检查方法步骤和原理.     

控制机动车辆保险经营风险的若干对策

机动车辆以其事故频发、损失严重的客观事实决定了这一险种存在的种种风险。客观分析机动车辆保险的现状和存在的种种风险，并就其存在的风险提出对策，完善风险管理整体功能，构筑风险管理工程。     

Motor skills, automaticity and developmental dyslexia: A review of the research literature

This paper reviews a body of prominent theoriesof automaticity in developmental dyslexia. Thefirst part of the review considers therelationship between dyslexia and rapidautomatic naming and fluency. Additionaltheoretical and empirical advances aresuggested to this already strong research base.In particular, there is a need is forexperimental work elucidating the nature ofnaming speed deficits and providing independentevidence of the automaticity of rapid naming.The second part of the review considersevidence for deficits in motor automaticity indyslexic children. Here, a more mixed patternof results is evident. It is concluded thatthere is currently clearer evidence forlanguage-based than motor-based automaticitydeficits. Future motor automaticity research islikely to require the routine screening of poorreaders for common co-occurring developmentaldifficulties, improved sampling and prospectivelongitudinal studies.     

永磁同步电机调速的预测电流控制方法

为解决永磁同步电机(Permanent Magnet Synchronous Motor,PMSM)的非线性和强耦合性,根据PMSM的特性,在MATLAB/Simulink环境下建立数学模型并进行离散化,设计预测控制与矢量控制相结合的PMSM电流控制方法.仿真结果表明,该方法对于PMSM调速系统具有良好的控制性能.     

记忆巩固：动作技能学习研究热点与展望

离线学习和记忆稳定作为记忆巩固较为明显的两个行为特征,在动作技能学习研究领域日益受到重视,并产生了一定数量且极具理论与实践价值的研究成果。参阅该领域新近开展的研究工作,就睡眠与离线学习、动作技能学习与后摄抑制以及运动干预与记忆稳定等方面的研究现状加以梳理和述评。结果显示：当前动作技能学习中记忆巩固的相关研究还存在研究方法单一,实验设计相互模仿和照搬;研究范围不够全面,深度和广度有所欠缺;研究任务特征系统性不强等不足。在此基础上,对运动技能学习中记忆巩固研究的发展趋势进行了展望。     

The myth of contextual interference learning benefit in sports practice: A systematic review and meta-analysis

The contextual interference (CI) model hypothesizes random practice (high CI) leads to inferior acquisition, but superior retention and transfer capabilities compared to blocked practice (low CI). These phenomena are well established in laboratory settings. However, the transfer to applied settings, particularly in sports practice is still under discussion. The aim of this systematic review and meta-analysis is to evaluate the possible generalisability of the CI phenomenon in sports-based contexts with regard to performance outcomes. Up to April 16th, 2022, five electronic databases (PubMed, Web of Science, Scopus, Taylor & Francis, and SciELO) were used to search for relevant studies investigating differences between blocked and random schedules at post-acquisition, retention, and/or transfer tests. Using the PICOS criteria, a total of 933 records were screened. Outcomes evaluating the acquisition, retention, and/or transfer performances in sports skills in healthy participants were included. The quality of the selected studies was scored using the PEDro scale. Thirty-seven studies were selected, of which twenty-seven were of good quality and the remaining ten were rated as fair quality. Out of 205 overall pooled outcomes, only 43 performance outcomes (21%) agreed with the CI phenomenon after the acquisition (18 out of 103), retention (19 out of 84), and/or transfer (6 out of 36) phases. No statistically significant overall difference between blocked and random practice was detected at post-acquisition (effect size (ES) = 0.1, p = 0.154), retention (ES = −0.159, p = 0.141) or transfer testing (ES = −0.243, p = 0.071). The subgroup analysis showed inferior acquisition and superior retention following random practice only in individuals aged 20–24 years (ES = 0.282, p = 0.030 during the acquisition, and ES = −0.405, p = 0.011 during retention), with no difference at transfer testing for this specific age group. No similar significant effects have been concurrently identified during both acquisition and retention phases in any of the remaining subgroups (e.g., examined based on experience level, sports, skills, and testing protocol categories). The present results suggest CI effects can only be confirmed under very limited conditions, which seriously challenges the extension of CI effects to the sport context in general. Problematic conclusions for children's learning are discussed, as well as future research strategies to better understand counterintuitive learning approaches.     

TCACNet: Temporal and channel attention convolutional network for motor imagery classification of EEG-based BCI

Brain–computer interface (BCI) is a promising intelligent healthcare technology to improve human living quality across the lifespan, which enables assistance of movement and communication, rehabilitation of exercise and nerves, monitoring sleep quality, fatigue and emotion. Most BCI systems are based on motor imagery electroencephalogram (MI-EEG) due to its advantages of sensory organs affection, operation at free will and etc. However, MI-EEG classification, a core problem in BCI systems, suffers from two critical challenges: the EEG signal’s temporal non-stationarity and the nonuniform information distribution over different electrode channels. To address these two challenges, this paper proposes TCACNet, a temporal and channel attention convolutional network for MI-EEG classification. TCACNet leverages a novel attention mechanism module and a well-designed network architecture to process the EEG signals. The former enables the TCACNet to pay more attention to signals of task-related time slices and electrode channels, supporting the latter to make accurate classification decisions. We compare the proposed TCACNet with other state-of-the-art deep learning baselines on two open source EEG datasets. Experimental results show that TCACNet achieves 11.4% and 7.9% classification accuracy improvement on two datasets respectively. Additionally, TCACNet achieves the same accuracy as other baselines with about 50% less training data. In terms of classification accuracy and data efficiency, the superiority of the TCACNet over advanced baselines demonstrates its practical value for BCI systems.     

The influence of gate start position on physical performance and anxiety perception in expert BMX athletes

The critical importance of the start phase in bicycle motocross (BMX) racing is increasingly acknowledged. Past experiments underlined that the internal lane of the starting gate provides a strong positional advantage. However, how lane position affects start performance and cognitive and somatic state anxiety remains unexplored. We examined the start performance and anxiety responses of youth national-level BMX riders in both experimental and ecological contexts. We used contextualization motor imagery routines to evaluate start performance and state anxiety from the internal and external lanes. Cycle ergometer measures revealed a better start performance from the external lane, but we did not record any lane effect on actual gate start times. Both somatic and cognitive anxiety scores were higher before racing from the internal compared to the external lane. Finally, state anxiety (i.e., somatic anxiety, worry and concentration disruptions) negatively predicted the start performance. Present findings provide original insights on psychological factors involved in BMX start performance, and might contribute to fruitful coping interventions and training programmes in sports overlapping the framework of “handicap races” taking the specific form of positional advantages/disadvantages at the start (e.g., ski/snowboard cross, athletics, swimming, motorsports, etc.).     

Comparison of motor competence levels on two assessments across childhood

This study compared performances and motor delay classifications for the Test of Gross Motor Development-2nd edition (TGMD-2) and the Körperkoordinationstest Für Kinder (KTK) in a sample of 424 healthy children (47% girls) between 5 and 10 years of age. Low-to-moderate correlations (r range = 0.34–0.52) were found between assessments across age. In general, both boys and girls demonstrated higher raw scores across age groups. However, percentile scores indicated younger children outperformed older children, denoting a normative percentile-based decrease in motor competence (MC) in the older age groups. In total, the TGMD-2 and KTK classified 39.4% and 18.4% children, respectively, as demonstrating very low MC (percentile ≤5). In conclusion, the TGMD-2 classified significantly more children with motor delays than the KTK and the differences between children’s motor skill classification levels by these assessments became greater as the age groups increased. Therefore, the TGMD-2 may demonstrate more susceptibility to sociocultural influences and be more influenced by cumulative motor experiences throughout childhood. Low-to-moderate correlations between assessments also suggest the TGMD-2 and KTK may measure different aspects of MC. As such, it may be important to use multiple assessments to comprehensively assess motor competence.     

永磁同步电机速度环的滑模变结构控制

在永磁同步电机解耦数学模型的基础上,本文提出了一种把滑模变结构原理用于永磁同步电机的矢量控制系统的方法。首先详细阐述了滑模变结构的基本原理,然后采用速度环的滑模变结构来取代传统的PI控制,并对两个系统进行了仿真分析,仿真结果证明采用速度环的滑模变结构控制系统确有其优越性。