测试双向可控硅输出电压波形对称性的简便方法

重点介绍使用万用表测量双向可控硅输出电压波形对称性的简单方法.     

数学学习困难儿童的多媒体教学策略

如何对数学学习困难儿童进行有效干预是很多教育工作者关心的问题。已有研究表明,工作记忆的缺陷是数学学习困难的根本原因。而基于认知负荷理论的教学设计正是针对人的工作记忆容量有限这一特点,利用多媒体来促进意义学习的完成。文章试图以工作记忆为桥梁,结合认知负荷理论,提出几条针对数学学习困难儿童的多媒体教学的干预措施,并指出了将来的研究方向。     

基于交-交变频技术实现异步电动机重载起动的研究

为解决异步电动机重载起动存在的不足,提出了一种以80C196KC DSP为控制技术的交-交变频系统的实现方法.该方法具有起动电流小、启动转矩大、启动平滑、运行稳定、控制效果好的特点,详细阐述系统主电路及控制部分的原理和实现方法.     

Load reduction instruction: Exploring a framework that assesses explicit instruction through to independent learning

Load reduction instruction (LRI) is an instructional approach aimed at managing the cognitive burden on students in the initial stages of learning; then, as fluency and automaticity develop, students are encouraged to engage in guided independent learning. LRI comprises five factors: difficulty reduction, support and scaffolding, practice, feedback, and guided independence. This study examined an instrument (the Load Reduction Instruction Scale, LRIS) aimed at assessing these five factors. Among a sample of high school students from 40 classrooms, findings supported the validity of the LRIS, the conceptualising underpinning it, and its potential to guide instructional practice.     

Force–velocity property of leg muscles in individuals of different level of physical fitness

The present study explored the method of testing muscle mechanical properties through the linear force–velocity (F–V) relationships obtained from loaded vertical jumps. Specifically, we hypothesised that the F–V relationship parameters depicting the force, power, and velocity of the tested muscles will differ among individuals of different physical fitness. Strength trained, physically active, and sedentary male participants (N = 10 + 10 + 10; age 20–29 years) were tested on maximum countermovement and squat jumps where manipulation of external loads provided a range of F and V data. The observed F–V relationships of the tested leg muscles were approximately linear and mainly strong (median correlation coefficients ranged from 0.77 to 0.92; all p < 0.05), independently of either the tested group or the jump type. The maximum power revealed higher values in the strength trained than in the physically active and sedentary participants. This difference originated from the differences in F-intercepts, rather than from the V-intercepts. We conclude that the observed parameters could be sensitive enough to detect the differences among both the individuals of different physical fitness and various jump types. The present findings support using loaded vertical jumps and, possibly, other maximum performance multi-joint movements for the assessment of mechanical properties of active muscles.     

可变负载非接触电能传输系统的无功功率补偿

为解决非接触电能传输系统中负载电阻变化会导致系统传输能力变化的问题,研究非接触电能传输系统在并联—串联拓扑下负载变化时无功功率的补偿问题.通过分析理想可变初级电容的可控性,提出用积分控制器对可控电抗器进行动态调节以完成负载变化时的无功功率补偿.数值仿真表明,该控制方案是可行的.     

基于区域分流的低轨卫星星座星间负载均衡路由算法

低轨卫星通信网络具有流量分布不均、地面站分布不均且网络负载随时间变化等特点.卫星与就近地面站间的数据传输将会导致空间段动态漏斗型拥塞,进而引发馈线拥塞并劣化端到端通信指标.提出基于区域分流的多径搜索负载均衡路由算法(regional-traffic-detour multipath search load balanc...     

中长跑项目多课次训练模式

对中长跑“多课次”训练的概念、必要性、生理学基础等进行较为详细的论述，并对“多课次”训练计划的安排及应注意的问题作了说明，旨在丰富中长跑训练的方法手段，保证训练的质量，尽快提高成绩。研究认为。中长跑采用“多课次”训练是可行的。也是必要的，是科学化运动训练的一大体现。建议：“多课次”训练时间的安排，应突破传统的条条框框。在全天24小时内合理安排。实践中逐步摸索出适合每位运动员最为科学的训练课次及运动负荷量。     

运动性膝关节损伤的临床康复

针对膝关节不稳定性损伤的不同状态,对不同运动强度,不同运动开始时间在损伤康复研究中的价值进行比较研究,为运动性膝关节损伤的临床康复提供参考。     

机械零件随机疲劳载荷的统计分析方法

研究了机械零件载荷的时间历程特性，分析了随机载荷的循环计数法、峰值计数法和雨流计数法等统计分析方法，提出了随机疲劳载荷的概率分布函数及疲劳载荷谱的编制方法。