An optimal quality adaptation mechanism for end-to-end FGS video transmission

In this paper, we propose a novel optimal quality adaptation algorithm for MPEG-4 fine granular scalability (FGS) stream over wired network. Our algorithm can maximize perceptual video quality by minimizing video quality variation and increasing available bandwidth usage rate. Under the condition that the whole bandwidth evolution is known, we design an optimal algorithm to select layer. When the knowledge of future bandwidth is not available, we also develop an online algorithm based on the optimal algorithm. Simulation showed that both optimal algorithm and online algorithm can offer smoothed video quality evolution.     

A bridge over troubled waters: Bridging organisations and entrepreneurial opportunities in emerging sectors

Bridging institutions or organisations are regarded as having positive effects in the Sectoral Systems of Innovation (SSI) literature, particularly in compensating for weaknesses in these systems. Yet, we know little about the organisational practices that make their role effective, or the types of innovation paths that they may facilitate within a system. This paper shows how bridging organisations may promote neglected areas of creativity and potential disruptive innovation. These blocked opportunities tend to emerge at the boundaries of SSI: where old sectors overlap and new trajectories form. We draw on the social networks, entrepreneurship and disruptive innovation literature and analyse an intervention in the UK electronic games industry: the evaluation of business propositions exploiting new gaming platforms such as mobile telephones, DVD and film. Using an innovative co-productive research design, the study shows how the effectiveness of bridging organisation activity depends on key design choices and brokerage capabilities.     

Mathematics teachers’ “learning to notice” in the context of a video club

This study examines changes in teachers’ thinking as they participated in a video club designed to help them learn to notice and interpret students’ mathematical thinking. First, we investigate changes in teachers’ talk about classroom video segments before and after participation in the video club. Second, we identify three paths along which teachers learned to notice students’ mathematical thinking in this context: Direct, Cyclical, and Incremental. Finally, we explore ways the video club context influenced teacher learning. Understanding different forms of teacher learning provides insight for research on teacher cognition and may inform the design of video-based professional development.     

Video as a tool for fostering productive discussions in mathematics professional development

This article explores the use of classroom video as a tool for fostering productive discussions about teaching and learning. The setting for our research is a 2-year mathematics professional development program, based on the Problem-Solving Cycle model. This model relies on video from the teachers’ own classrooms and emphasizes creating a community in which members feel comfortable learning from video. We describe our experiences carrying out the Problem-Solving Cycle model, focusing on our use of video, our efforts to promote a supportive and analytical environment, and the ways in which teachers’ conversations around video developed over a 2-year period.     

在线考试系统中防作弊措施的应用

在线考试在现代化教育中得到了广泛应用。为了进一步提高在线考试的公平、公正性,弥补传统考试人工监考的不足,对在线考试的防作弊功能进行了深入的分析,给出了详细的功能设计与实现思路。     

Sport and re/creation: what skateboarders can teach us about learning

This paper explores the role of digital media and creativity in the processes of learning that occur in groups of urban skateboarders. In particular, it examines how the production and consumption of amateur videos contribute to both skaters’ mastery of the techniques of the sport and their integration into the culture of the sport. The data come from an ethnographic study of skateboarders in Hong Kong, which included in-depth interviews, participant observation and the collection of texts and artifacts like magazines, blog entries and amateur skating videos. Skateboarders use video in a number of ways that significantly impact their learning and integration into their communities. They use it to analyze tricks and techniques, to document the stages of their learning and socialization into the group, to set community standards, to build a sense of belonging with their ‘crews’ and to imagine ‘idealized futures’ for themselves and their communities. Understanding the value and function of such ‘semiotic mediation’ in learning and socialization into sport cultures, I suggest, can contribute to helping physical educators design tasks that integrate training in physical skills with opportunities for students to make meaning around their experiences of sport and physical education.     

多特征视频分类挖掘实验研究

主要描述笔者进行的分类挖掘研究实验。该实验基于北卡罗来纳大学(UNC)的Open Video项目,使用支持向量机对抽取的低层视觉和高层语义特征进行挖掘,考察不同类型的关键帧集合对于分类结果的影响并全面比较各种类型的特征及不同组合在分类中的贡献。结果表明,基于多特征的视觉和文本的结合能够取得较好的分类结果;此外,关键词和描述对挖掘效果具有不同影响。     

网络环境下自主学习监控模式建立与研究

结合当前大学英语教学改革的趋势,以网络为支撑的新型大学英语教学模式,以学生为中心的个性化教学已成为主体。开发一个能对学生自主学习过程信息的采集工具与处理,作出快捷有效的监控评价方式显得尤其重要。文章阐述了如何通过软件工具对网络环境下自主学习过程的点击信息进行采集,并为学生登录行为实施有效评价提供基础数据。     

Complexity of visual learning material moderates the effects of instructor's beat gestures and head nods in video lectures

Instructors often show rhythmic movements with speech in video lectures. However, the effects of these movements have not been tested in video lectures with an instructor and visual learning material. Results of Experiment 1 showed students in the beat gestures and head nods conditions showed significantly less attention to the visual learning material, more attention to the instructor, whereas in the beat gestures + head nods condition drew significantly more attention to both. In Experiment 2 we tested whether the complexity of the visual learning material moderated the effects of rhythmic movements on students’ learning. When the presentation was simple, students in the head nods + beat gestures condition showed more positive interaction, and significantly better recall and transfer. The results have implications for video designing: if an instructor and simple learning material are visible, she is encouraged to show beat gestures and head nods to mark important information.     

Rate-distortion optimized frame dropping and scheduling for multi-user conversational and streaming video

INTRODUCTION Video packets are transmitted over the Internet using a best-effort service. Therefore, a large number of simultaneous video streams or cross traffic arriving at a network node (e.g. a multimedia gateway) may sometimes exceed the node’s forwarding capacity, i.e., the incoming data rate may exceed the outgoing data rate at the node. In this paper, we consider a scenario where M streaming videos and N conversa- tional videos pass through a network node with lim- ited forwardi…