新规则、新赛制下中外乒乓球运动员的战术应用比较

采用录像观察法和三段分析法,对国外优秀乒乓球运动员男子10人,女子11人共47场比赛进行分析,在此基础上结合张晓蓬(2004)的研究对中外优秀乒乓球运动员在新规则和新赛制下的战术应用情况进行对比分析。结果发现中国运动员在三段中的得分率明显高于国外选手,但在发球抢攻段的使用率较国外运动员低。研究还发现,国外男、女选手在三段的大多数指标中没有表明出明显的差异。男选手的技术优势主要体现在接发球段的得分能力上。     

If we built it,would they come? Creating instruction videos with promotion in mind

This article reports on a video project done in an academic library where faculty were included in the production and marketing of the library instruction videos. The videos allowed the librarian to provide a shorter presentation and spend most of her time working individually with each student. The results showed that 97% of the students watched the videos and were able to benefit from the content. The implementation of the videos was a success due to the collaboration of the professors teaching the three courses and the buy-in of the course coordinator; both factors were essential in the success of the video project.     

Bullying and the Unique Socioemotional Needs of Gifted and Talented Early Adolescents: Veteran Teacher Perspectives and Practices

Much is written at the elementary school level concerning bullying and the socioemotional needs of gifted and talented (GT) students; however, in the last 10 years, little qualitative research exists concerning the early adolescent GT age group. In the social environment of classroom life, early and current research indicates that many of these students experience neurotic perfectionism, overexciteabilities (OEs), developmental asynchrony, and bullying. The formation of autonomous classes (GT-only classes) has afforded some hope concerning the amelioration of such problems; nevertheless, in this study, detailed evidence of classroom bullying in the form of social ostracism and teasing has been found with this GT age group. If left unchecked, psychological autopsies have shown these students suffering emotional difficulties and even committing suicide as a result of school and classroom torment. With such potential for classroom bullying problems, few studies address what veteran teachers of early adolescent GT students do to keep students psychologically safe. Within the social milieu of classroom life, and in comparison to research standards, this study explores three efficacious teacher perspectives and practices.     

Social Constructivism and Asynchronous Text-Based Discussion: A Case Study with Trainee Teachers

The paper reports a case study using asynchronous text-based discussion. It considers the role of the tutor and discusses the extent to which online discussions can facilitate social constructivist approaches to instruction and the creation of knowledge. Participants were 17 trainee teachers studying on a post graduate teaching course. The asynchronous text-based discussion (using e-blackboard) focused on planning for progression in children's learning in history and culminated in the trainee teachers writing individual assignments on the topic. The paper analyses the different types of contributions made and reports on the trainees' evaluations of the benefits and limitations of using e-blackboard. It concludes with recommendations and areas for further research.     

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.     

变频器三相信号源发生器研究

低频信号发生器作为信号源历来受到微电子技术的从业人员关注,三相低频信号源更是从事控制系统设计的工程技术人员首选工具。长期以来,人们一直试图通过电子线路制作三相低频信号源,可效果不尽人意。利用单片机作为三相低频信号源的核心部件不但保证了三相低频信号的完整、稳定,还能实现频率从0～50Hz的任意调节。利用单片机的定时器作为频率控制,利用单片机的输入输出口作为三相信号输出是设计的初衷,通过反复实验后认定利用单片机作为三相低频信号源的设计是可行。利用单片机作为三相低频信号源发生器的关键技术是程序设计,程序设计的核心的三相方波之间的相序和频率的可调性。     

异步电机驱动时起升机构电机联轴器承受的载荷

本文介绍了应用异步电动机驱动的起重机起升机构在起动时,线弹性和非线弹性联轴器中冲击扭矩的确定方法。 在起重机起升机构两自由度简化力学模型的基础上,建立非线性振动微分方程,采用Runge-Kutta数值积分方法在IBM-PC微型计算机上求得系统的动载响应,同时对系统参数作了特征值化处理;并在此基础上,得到了载荷峰值函数线图。本文还提出了借助于载荷峰值函数来确定联轴器承受的冲击扭矩的方法。     

社交网络舆情下的二元信息竞争SH2IR模型及仿真研究

[研究目的]网络舆情中信息间的竞争传播更符合社交网络的真实情境,研究舆情事件中多元信息竞争传播的演化机制有助于政府和媒体有效监控舆情、引导舆论。[研究方法]结合舆情事件多信息传播特点,加入信息犹豫者和信息接触率,构建二元信息竞争的SH2IR模型,仿真同步和异步情景下二元信息的竞争演化过程。[研究结论]研究表明,在同步传播模式下,单独增强信息接触率、传播转化率、犹豫转化率以及置换率,都可以扩大信息的传播;在异步传播模式下,信息发布的越早,传播范围越广,但单独增强传播参数对传播效果影响较弱,同时提高信息的传播参数时传播行为明显加强。     

新规则对世界乒乓球运动技术发展趋势的影响

运用录像观察和三段分析法对实行新规则后的14名世界优秀男选手的比赛情况进行了统计分析,并将所得数据与各评估指标进行对比,结果发现:1)新规则执行后世界优秀男乒选手在三段使用率上发生了新的分配形式,三段的使用率有明显的"向平均数回归"的趋势.该结果提示新规则实施后,世界优秀选手在前三板的争夺更加激烈.2)与国外运动员相比,中国选手在接抢段的使用率更高,表明中国运动员更好地适应了新规则.此外,多名世界顶尖球手在相持段得分率的评估中不及格,作者据此认为新规则实施后,三段分析法的评估标准有必要进行修订,以跟上形式发展的需要.     

无线网在现代组网中的应用方案

无线局域网组网技术的发展和逐步成熟,推动了其在应用领域的普及,特别是在家庭组网中的应用。通过对无线局域网的发展、连接及标准ATM技术的应用探究,使无线局域网得到完善,进一步分析其优缺点和发展前景,为实际的应用提供一种理论指导。