Adaptive progressive download based on the MPEG-4 file format     

Färber Nikolaus  Döhla Stefan  Issing Jochen 《浙江大学学报(A卷英文版)》2006,7(1):106-111

In this paper we describe how progressive download and adaptive streaming can be combined into a simple and efficient streaming framework. Based on the MPEG-4 file format (MP4) we use HTTP for transport and argue that these two components are sufficient for specifying an open streaming architecture. The client selects appropriate chunks from the MP4 file to be transferred based on (1) the header information (i.e. the “moov” box) in the first part of the file and (2) his observation of network throughput. The framework is completely client driven which allows for better server scalability and reduces signalling overhead. We discuss architecture and implementation issues such as complexity, interoperability and scalability and compare to 3GPP PSS Rel-6 adaptive streaming when appropriate. Measurements from a simple MP4/HTTP streaming client are presented showing that appropriate chunks are selected such that increased reliability is achieved.  相似文献   

Der Mathematikunterricht der PISA-Schülerinnen und -Schüler     

Mareike Kunter  Martin Brunner  Jürgen Baumert  Uta Klusmann  Stefan Krauss  Werner Blum  Alexander Jordan  Michael Neubrand 《Zeitschrift für Erziehungswissenschaft》2005,8(4):502-520

Der Beitrag besch?ftigt sich mit dem Mathematikunterricht der PISA-Schülerinnen und -Schüler in Deutschland und berichtet über Ergebnisse aus einer Zusatzstudie zu PISA 2003. Aufbauend auf der mathematik-didaktischen Rahmenkonzeption von PISA, die Unterricht als Gelegenheitsstruktur für verst?ndnisvolle Lernprozesse versteht, wurden Schülerinnen und Schüler und ihre Mathematiklehrkr?fte zu Merkmalen der Unterrichtsqualit?t befragt. Es zeigen sich schulformspezifische Unterrichtskulturen: Ein kognitiv aktivierender Umgang mit mathematischen Inhalten ist eher in Gymnasien zu beobachten, w?hrend vor allem in Hauptschulen die Unterrichtsform mit geringem kognitiven Gehalt und ausgepr?gter Unterstützung überwiegt. Dennoch wird die Angebotsstruktur des Mathematikunterrichts von Jugendlichen an Hauptschulen positiv beurteilt, w?hrend Gymnasiasten ihren Unterricht eher kritisch bewerten. Diese Differenzen sind vor allem durch Unterschiede in der individuellen Lernunterstützung durch die Lehrkr?fte zu erkl?ren, welche von Schülerinnen und Schülern an Hauptschulen als besonders ausgepr?gt, an Gymnasien eher als gering beschrieben wird.  相似文献   

Development & validation of scientific video vignettes to promote perception of authentic science in student laboratories     

Insa Stamer  Hanno Pönicke  Frederike Tirre  Antti Laherto  Tim Höffler  Stefan Schwarzer 《Research in Science & Technological Education》2020,38(2):168-184

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Prediction of elementary mathematics grades by cognitive abilities     

Hilbert  Sven  Bruckmaier  Georg  Binder  Karin  Krauss  Stefan  Bühner  Markus 《European Journal of Psychology of Education - EJPE》2019,34(3):665-683

European Journal of Psychology of Education - In the present study, the relationship between the mathematics grade and the three basic cognitive abilities (inhibition, working memory, and...  相似文献   

水文预报的时间序列神经网络模型     

钟登华  刘东海  Mittnik Stefan 《天津大学学报(英文版)》2001,7(3):182-186

时间序列分析在水文预报中起重要作用 ,其关键是要建立一个合适的预报模型 .文章提出基于 BP算法的单输出和多输出水文预报时间序列神经网络模型 ,克服了以往多种基于随机分析预报模型的缺点 ,不仅能实现快速灵活的信息处理 ,而且具有很强的非线性映射和自学习、自适应能力 ,这为更精确描述复杂非线性水文过程提供了可能 .通过对历史数据的学习 ,模型可对水文径流量时间序列进行预报 ,两个实例分析表明模型的可行性和有效性  相似文献   

Posthumanism and educational research     

Stefan Herbrechter 《Educational Philosophy and Theory》2017,49(11):1125-1127

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Can typical game features have unintended consequences? A study of players’ learning and reactions to challenge and failure in an educational programming game     

Catherine C. Chase  Laura J. Malkiewich  Alison Lee  Stefan Slater  Ahram Choi  Chenmu Xing 《British journal of educational technology : journal of the Council for Educational Technology》2021,52(1):57-74

It is difficult to motivate learners to seek out and persist at challenging learning tasks where failure is likely. However, in game environments, people seem highly motivated to engage with challenges and respond productively to failure. Many typical game features purportedly enhance intrinsic motivation and self-efficacy, which should improve students’ reactions to challenge and failure, which should in turn enhance learning. An experimental study with early middle school students tested these assumptions by comparing a “Full” version of a typical, commercial programming game to a “Minimal” version of the same game where common game features such as narrative, performance metrics, high-quality graphics, and sound were removed. In contrast to our hypotheses, players of the Full Game were less likely to choose coding challenges, were less tolerant of coding failures and gained less coding knowledge. Intrinsic motivation and self-efficacy did not differ between conditions. Correlational analyses showed that failure tolerance and challenge seeking may critically affect learning from educational games. The current study offers an existence proof that some common game features can hinder players' failure tolerance, challenge-seeking and learning, in certain game contexts. Future research should isolate the effects of individual game features, test generalizability and explore which contextual variables influence the findings.  相似文献   

Adaptive progressive download based on the MPEG-4 file format   总被引：1，自引：0，他引：1  

FRBER Nikolaus  DHLA Stefan  ISSING Jochen Multimedia Transport  Dept. Audio  Fraunhofer Institute for Integrated Circuits IIS  Erlangen  Germany 《浙江大学学报(A卷英文版)》2006,7(Z1)

In this paper we describe how progressive download and adaptive streaming can be combined into a simple and efficient streaming framework. Based on the MPEG-4 file format (MP4) we use HTTP for transport and argue that these two components are sufficient for specifying an open streaming architecture. The client selects appropriate chunks from the MP4 file to be transferred based on (1) the header information (i.e. the "moov" box) in the first part of the file and (2) his observation of network throughput. The framework is completely client driven which allows for better server scalability and reduces signalling overhead. We discuss architecture and implementation issues such as complexity, interoperability and scalability and compare to 3GPP PSS Re1-6 adaptive streaming when appropriate. Measurements from a simple MP4/HTTP streaming client are presented showing that appropriate chunks are selected such that increased reliability is achieved.  相似文献   

International large-scale assessments: what uses,what consequences?     

Stefan Johansson 《Educational research; a review for teachers and all concerned with progress in education》2016,58(2):139-148

Abstract

Background: International large-scale assessments (ILSAs) are a much-debated phenomenon in education. Increasingly, their outcomes attract considerable media attention and influence educational policies in many jurisdictions worldwide. The relevance, uses and consequences of these assessments are often the focus of research scrutiny. Whilst some argue that the assessment outcomes provide an effective basis for informed policy-making, critics claim that the use of international assessment data can result in a range of unintended consequences, such as the shaping and governing of school systems ‘by numbers’.

Purpose: This article explores and analyses the arguments about the uses and consequences of ILSAs. In particular, the discourse about the assessments’ consequential validity will be discussed and evaluated.

Sources of evidence: Literature relating to the uses and consequences of large-scale assessment was analysed, with a focus on research on the consequential aspects of validity.

Main argument: Much research suggests that ILSAs have unintended consequences that affect and influence educational policy. However, the influences on educational policy are complex and interwoven: for example, it is not clear-cut whether effects such as converging curricular are, necessarily, direct consequences of large-scale assessments. Further, it is suggested that a beneficial consequence of large-scale assessment is the infrastructure they provide for studies in the social sciences, although caution must be applied to causal claims, in particular because of the cross-sectional design of the assessments.

Conclusions: The considerable literature discussing the uses and consequences of large-scale assessments tends to point out potential negative aspects of the studies. However, it is also apparent that large-scale international assessments can be a valuable resource for studying global trends and evolving systems in education. Despite the extensive debates around large-scale assessment outcomes both in the media and in educational policy arenas, empirical educational research all too often appears underused in the discussion.  相似文献   

How University Websites’ Emphasis on Age Diversity Influences Prospective Students’ Perception of Person-Organization Fit and Student Recruitment     

Toni A. Ihme  Katharina Sonnenberg  Maria-Luisa Barbarino  Björn Fisseler  Stefan Stürmer 《Research in higher education》2016,57(8):1010-1030

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