一种凸轮升程误差的非接触式测量新方法

分析现有几种凸轮升程误差测量方法的优、缺点后，提出一种基于图像处理的凸轮升程误差的非接触式测量新方法．理论分析和比较实验结果表明，该测量方法简便易行，测量精度较高，具有一定的应用价值．     

Assessment of three-dimensional joint kinematics of the upper limb during simulated swimming using wearable inertial-magnetic measurement units

The analysis of the joint kinematics during swimming plays a fundamental role both in sports conditioning and in clinical contexts. Contrary to the traditional video analysis, wearable inertial-magnetic measurements units (IMMUs) allow to analyse both the underwater and aerial phases of the swimming stroke over the whole length of the swimming pool. Furthermore, the rapid calibration and short data processing required by IMMUs provide coaches and athletes with an immediate feedback on swimming kinematics during training. This study aimed to develop a protocol to assess the three-dimensional kinematics of the upper limbs during swimming using IMMUs. Kinematics were evaluated during simulated dry-land swimming trials performed in the laboratory by eight swimmers. A stereo-photogrammetric system was used as the gold standard. The results showed high coefficient of multiple correlation (CMC) values, with median (first–third quartile) of 0.97 (0.93–0.95) and 0.99 (0.97–0.99) for simulated front-crawl and breaststroke, respectively. Furthermore, the joint angles were estimated with an accuracy increasing from distal to proximal joints, with wrist indices showing median CMC values always higher than 0.90. The present findings represent an important step towards the practical use of technology based on IMMUs for the kinematic analysis of swimming in applied contexts.     

Accelerometer data requirements for reliable estimation of habitual physical activity and sedentary time of children during the early years - a worked example following a stepped approach

This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC’s (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion.     

蔬菜栽培课程产学合作教育的实践与思考

选择具有日光温室、塑料大棚、中棚及露地等多种生产方式，蔬菜种类较多，面积较大，种植蔬菜历史较长，交通便利的村寨作为蔬菜栽培课程产学合作教育的基地。把学生分配到农户，每户3～4名学生为一组，与蔬菜生产实际紧密结合，让学生接受培养土的配制，种子处理与播种，苗床管理，定植，田间管理及嫁接育苗等环节的训练。结果表明：学生获得了两个层面的训练。在第一个层面上，学生熟练掌握了蔬菜栽培基本环节的技术要求和要领，动手能力得到明显提高，培养了学生的基本技能；在第二个层面上，学生掌握了蔬菜设施栽培、无公害生产综合配套等高层次技术，培养了学生综合技术应用能力。今后应特别注意学生和生产者(企业或农户)的双向参与，信息的双向传递，学校与生产者(或企业或农户)双赢，以及培养学生创新能力即第三个层面的训练。     

2014年女排世锦赛中国女排主攻队员扣球技术分析

运用文献资料法、比较分析法、数理统计法、录像分析法、逻辑分析法对中国女排在2014年世界女排锦标赛13场对抗赛中的主力主攻手的扣球技术统计分析,认为中国女排主攻手进攻位置比较单一,提出两主攻手在平时训练中应加强各种训练等建议。     

加强电子技术实验课改革的几项措施

文章指出了目前高校电子技术实验课中普遍存在的一些问题以及加强本课程实验改革的必要性，并提出了几项改革措施。     

中小学音乐教师:新课程实施的调适

音乐基础课程改革对中小学音乐教师提出了全新的要求。本文从教师理念的更新、教师自身知识技能的调适、教学模式的转换三方面，论述了中小学音乐教师在新课程实施过程中应进行的调整与适应。     

虚拟制造技术及其在制造业中的应用

从虚拟制造的形成背景,介绍了虚拟制造的特点、分类;并对虚拟制造的核心技术及理论体系等多方面进行详细阐述。最后就虚拟制造的应用和虚拟制造技术的发展潜力和国内外现状进行系统介绍。     

基于专利耦合的 中国、美国、日本锂离子电池技术前沿及差距分析

基于定量分析识别技术前沿并测度各国的技术差距具有重要的理论和现实意义。本研究初步探讨了基于专 利数据,利用文献计量学的引文耦合分析法,进行技术前沿的识别和技术差距粗略测度,并以锂离子电池为例进行实 证研究。研究结果表明,该方法所识别出来的中国、美国和日本在锂离子电池领域的技术前沿以及各国之间的技术差 距,与产业现状具有一定一致性,是一条可行的研究途径。     

An Examination and Validation of an Adapted Youth Experience Scale for University Sport

Limited tools assess positive development through university sport. Such a tool was validated in this investigation using two independent samples of Canadian university athletes. In Study 1, 605 athletes completed 99 survey items drawn from the Youth Experience Scale (YES 2.0), and separate a priori measurement models were evaluated (i.e., 99 items, YES 2.0, YES for Sport [YES-S]). Confirmatory factor analysis (CFA) and exploratory structural equation modeling (ESEM) results indicated issues with model fit. Post-hoc modifications improved fit, resulting in a 46-item, 9-factor model with five positive and four negative dimensions. In Study 2, 511 athletes completed the same items. The resultant model was confirmed using both CFA (comparative fit index [CFI] = .911, standardized root mean square residual [SRMR] = .056, root mean square error of approximation [RMSEA] = .040) and ESEM (CFI = .956, SRMR = .023, RMSEA = .034). The resultant University Sport Experience Survey provides a reliable and factorially valid instrument for measuring development in university sport.