从复制技术看网络视频资源的获取

网络视频广泛应用在社会生活的各个领域,也是一种十分宝贵的信息资源。网络视频可以方便地被观看,但它的获取在很多时候却是不那么容易。针对不同的情况,我们需要采取不同的方式来获取网络视频资源。从节目复制技术的角度,文章探究了网络视频资源的三种获取形式:转录、收录和实录。     

视频技术在学校拉丁舞教学中的应用研究

运用文献资料法、访谈法、教学实验法,本研究以益阳市起点健身会所拉丁舞培训班的学生为实验对象,对视频技术在拉丁舞教学过程中进行了单因素试验研究。结果表明：视频技术可充分调动学生学习的积极性,提高记忆效果,从而提高课堂教学效率,增大课容量,实现资源的高度共享。     

Using VCDs to promote rural educational development in China: a case study in the Tianshui hilly areas of Gansu

This case study is set in a remote rural area of China—the Tianshui area of Gansu Province. It examines a strategy involving the use of Video Compact Discs (VCDs) to enhance primary education in these areas. Firstly, the challenging context of Tianshui area is described. Secondly, strategies for promoting rural education using VCDs and the initial successful experiences of the project are discussed. Finally, the challenges and issues of concerns are highlighted.     

Video-Based Analyses of Motivation and Interaction in Science Classrooms

An analytical framework for examining students’ motivation was developed and used for analyses of video excerpts from science classrooms. The framework was developed in an iterative process involving theories on motivation and video excerpts from a ‘motivational event’ where students worked in groups. Subsequently, the framework was used for an analysis of students’ motivation in the whole class situation. A cross-case analysis was carried out illustrating characteristics of students’ motivation dependent on the context. This research showed that students’ motivation to learn science is stimulated by a range of different factors, with autonomy, relatedness and belonging apparently being the main sources of motivation. The teacher’s combined use of questions, uptake and high level evaluation was very important for students’ learning processes and motivation, especially students’ self-efficacy. By coding and analysing video excerpts from science classrooms, we were able to demonstrate that the analytical framework helped us gain new insights into the effect of teachers’ communication and other elements on students’ motivation.     

Explanation-Construction in Fourth-Grade Classrooms in Germany and the USA: A cross-national comparative video study

To help explain the differences in students' performance on internationally administered science assessments, cross-national, video-based observational studies have been advocated, but none have yet been conducted at the elementary level for science. The USA and Germany are two countries with large formal education systems whose students underperform those from peers on internationally administered standardized science assessments. However, evidence from the 2011 Trends in International Mathematics and Science Exam assessment suggests fourth-grade students (9–10 year-olds) in the USA perform higher than those in Germany, despite more instructional time devoted to elementary science in Germany. The purpose of this study is to comparatively analyze fourth-grade classroom science in both countries to learn more about how teachers and students engage in scientific inquiry, particularly explanation-construction. Videorecordings of US and German science instruction (n _1?=?42, n _2?=?42) were sampled from existing datasets and analyzed both qualitatively and quantitatively. Despite German science lessons being, on average, twice as long as those in the USA, study findings highlight many similarities between elementary science in terms of scientific practices and features of scientific inquiry. However, they also illustrate crucial differences around the scientific practice of explanation-construction. While students in German classrooms were afforded more substantial opportunities to formulate evidence-based explanations, US classrooms were more strongly characterized by opportunities for students to actively compare and evaluate evidence-based explanations. These factors may begin to help account for observed differences in student achievement and merit further study grounded in international collaboration.     

Electromyographic analysis of exercise resulting in symptoms of muscle damage

Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad s -1 ) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.     

A qualitative investigation of the temporal patterning of the precompetitive anxiety response

The aim of this study was to examine retrospective perceptions and causal beliefs about temporal experiences of competitive anxiety and related symptoms in the lead up to competition. Qualitative interviews were conducted with 9 elite performers to examine the interaction of intensity, frequency and direction of symptoms associated with competitive anxiety before competition. Data analysis identified six causal networks that supported theoretical predictions suggesting that intensity of cognitive anxiety symptoms remained relatively stable in the lead up to competition, whereas somatic anxiety peaked sharply at the onset of performance. Frequency of anxiety symptoms increased as the competition approached and changes in interpretation of anxiety symptoms were also reported, with self-confidence identified as a moderating variable. The findings highlight the dynamic properties of the stress response and emphasize the need to consider the idiosyncratic nature of the level, frequency and interpretation of performers' precompetitive experiences.     

图书馆RFID系统建设的成效与发展思考

厦门图书馆引入RFID系统,使读者到馆数和文献借阅量大幅度增长,并带动了厦门区级图书馆自动化技术的发展。厦门图书馆在RFID系统建设的过程中发现,RFID技术需要不断的完善,并且需要建立统一的RFID技术标准,以实现厦门地区资源的共建共享。因此,厦门图书馆将以市馆为中心馆,建设厦门地区RFID系统的大流通服务体系,尝试利用智能书架系统提高工作效率,应用不停车即可还书的自助还书系统。     

高频小信号LC谐振放大器的设计

本文介绍了高频小信号LC谐振放大器的设计思路与具体电路实现,主要由衰减网络、LC谐振放大、电压跟随和电源四大模块组成。衰减器采用电阻式π型网络实现;LC谐振放大中选用功耗小的2N2222型三极管进行两级放大,LC谐振部分为放大器的负载;电压跟随采用集成运放OPA355,以实现电路阻抗的良好匹配;为了给放大器工作提供稳压电源,采用LM317稳压芯片设计了一个电源。经测试,放大器低功耗、高增益,具有良好的选择性。     

基于高速公路收费站视频监控图像的JPEG编码实现

高速公路收费站视频监控图像压缩的目的是将监控视频拍摄到的较大的图像用尽量少的字节来存储和传输,并且要求复原图像时能有较好的质量。本文采用JPEG编码方式实现了高速公路收费站视频监控实时图像压缩,通过JPEG编码减轻图像存储和传输的负担,使监控图像能够在网络上实现快速传输和实时处理。