动态雾计算网络中基于在线学习的任务卸载算法     

谭友钰  陈蕾  周明拓  王昆仑  杨旸  张武雄 《中国科学院大学学报》2020,37(5):688-698

任务卸载是雾计算的主要技术之一，即计算能力不足的节点将任务卸载给具有富余资源的节点帮助计算。以优化任务平均卸载时延和提升卸载服务成功率为目标，利用多臂老虎机理论为动态雾计算网络提出一种基于在线学习的任务卸载算法，可实时做出最优卸载决策。将该算法扩展到非稳定网络状态，使之可以动态追踪网络中节点的资源与环境变化，实时调整卸载决策。详细分析所提出算法的性能、复杂度和存储占用情况。仿真结果表明，这两种算法可达到的长期平均任务卸载时延均十分接近理想算法下的最优时延，卸载服务成功率也得到显著提升。此外，所提算法在非稳定的网络状态下能够追踪到计算资源与环境的变化。  相似文献   

Gender,complexity, and science for all: Systemizing and its impact on motivation to learn science for different science subjects          下载免费PDF全文

Albert Zeyer 《科学教学研究杂志》2018,55(2):147-171

The present study is based on a large cross‐cultural study, which showed that a systemizing cognition type has a high impact on motivation to learn science, while the impact of gender is only indirect thorough systemizing. The present study uses the same structural equation model as in the cross‐cultural study and separately tests it for physics, chemistry, and biology. The model was confirmed for physics and chemistry, but not for biology. This is interpreted as empirical evidence for a cognitive difference between the learning of hard sciences (like physics and chemistry) and life sciences (like biology) that reflects an epistemological difference between ordered (linear) and complex (non‐linear) systems. It is concluded that a more prominent inclusion of complex issues into science teaching could motivate low and average systemizers, independent of their gender, for science learning, that is, could be a key to science for all. Thus, there is a mutual benefit between important 21st century's issues of science teaching and the need to foster students’ motivation to learn science. © 2017 Wiley Periodicals, Inc. J Res Sci Teach 55: 147–171, 2018  相似文献   

Motivation counteracts fatigue-induced performance decrements in soccer passing performance     

Jeroen C.M. Barte  Arne Nieuwenhuys  Sabine A.E. Geurts  Michiel A.J. Kompier 《Journal of sports sciences》2019,37(10):1189-1196

Recent theories suggest that negative effects of fatigue on performance are determined by perception of effort and motivation rather than being directly caused by reaching physiological limits. In the current experiment, the influence of motivation on fatigue-induced decrements in soccer performance was experimentally investigated. Sixty amateur soccer players performed a validated soccer-passing test before and after a fatigue protocol. Results showed that players’ motivation and performance decreased after the fatigue protocol for players in the control group. In contrast, players in the motivation group (i.e., with motivation experimentally induced after the fatigue protocol) were able to uphold their motivation and increase their performance. These results indicate that motivation plays a crucial role in performance under fatigue, as fatigue-induced decrements in soccer passing performance can be counteracted by high levels of motivation. Future research may explore the limits of this counteracting effect and extend findings to other relevant performance aspects.  相似文献   

数据驱动的微信用户信息行为时间特征研究     

张大勇  孔洪新  许磊  景东 《图书情报工作》2019,63(20):104-111

[目的/意义]相对于传统的信息行为分析，数据驱动的信息行为研究更注重数据的外在性与客观性，所得的结果能够更为全面地认识用户信息行为本质特征。[方法/过程]通过自行构建的APP实现对微信用户分享和阅读行为记录的采集，并对微信用户信息行为的时间特性进行系统的分析。[结果/结论]结果表明：微信用户日常信息行为存在显著的假日效应，但是在信息行为时间间隔分布上存在明显厚尾现象和很强的阵发性，预示着微信用户信息行为具有较高的复杂性和不确定性，无法对其产生过程实现有效的预测；此外，微信用户所分享的内容具有很强的时效性，多数内容在微信中能够得到及时的传播，但传播链长度显著受分享内容主题的影响。  相似文献   

Hot hands,cold feet? Investigating effects of interacting constraints on place kicking performance at the 2015 Rugby Union World Cup     

Chris Pocock  Neil E. Bezodis  Keith Davids  Jamie S. North 《European Journal of Sport Science》2018,18(10):1309-1316

Place kicks in Rugby Union present valuable opportunities to score points outside the spatiotemporal dynamics of open play but are executed under varying performance constraints. We analysed effects of specific task constraints and relevant contextual factors on place kick performance in the 2015 Rugby Union World Cup. Data were collected from television broadcasts for each place kick. In addition to kick outcomes, contextual factors, including time of the kick in the match, score margin at the time of the kick, and outcome of the kicker’s previous kick, were recorded. Effects of spatial task constraints were analysed for each kick, using distance (m) and angle (°) of the kick to the goalposts. A binomial logistic regression model revealed that distance from, and angle to, the goalposts were significant predictors of place kick outcome. Furthermore, the success percentage of kickers who missed their previous kick was 7% lower than those who scored their previous kick. Place kick success percentage in the 10 minutes before half-time was 8% lower than the mean tournament success percentage, which was 75% (95% CI 71–78%). The highest kick success percentage was recorded when scores were level (83%; 95% CI 72–91%). Our data highlighted how subtle changes in task constraints and contextual factors can influence performance outcomes in elite performers in international competition. Fluctuations in place kick success suggested that individual constraints, such as thoughts, emotions and fatigue, induced during competition, could interact with perceptions to influence emergent performance behaviours.  相似文献   

The use of hypermedia in collaborative learning. An approach to the problem of complex systems in the teaching of urban planning / El uso de hipermedia en el aprendizaje colaborativo. Una aproximación al problema de los sistemas complejos en la docencia del urbanismo     

Carlos Rosa-Jimenez  Maria-José Marquez-Ballesteros  Nuria Nebot 《Cultura y Educación》2018,30(2):414-432

The counterpart to the open access to information facilitated by the Internet is the problem of the over-saturation of data and sources. A collaborative model of hypermedia is proposed as a pedagogical approach to the teaching of urban planning in which students organize and construct information from the possibilities provided by hypertext language. The methodology is structured in three phases: organization when searching for information; presentation of information using hypermedia; and assessment of the work. The results show that organization of information in the form of websites obtained the highest scores, although collaborative assessment should be restricted to subjective aspects of communication, while objective aspects should be assessed by the teacher and by groups of experts.  相似文献   

Understanding teacher collaboration processes from a complexity theory perspective: a case study of a Chinese secondary school     

Rui Yuan  Shulin Yu 《Teachers and Teaching》2018,24(5):520-537

Although research on teacher collaboration has proliferated in the last few decades, scant attention has been paid to the development of teacher collaboration in school contexts. Informed by the perspective of complexity theory, this study investigates the complex process of teacher collaboration through qualitative interviews in an English teaching research group (TRG) in a secondary school in China. The findings reveal three distinct stages in the development of teacher collaboration, labeled as ‘breaking the ice’, ‘everything is out of control’ and ‘learning how to collaborate through collaboration’. The study shows that teacher collaboration is an adaptive, complex system that evolves through internal self-organization and interaction with external stakeholders and systems, such as school management and university researchers. The study provides useful insights into the ways of facilitating and sustaining teachers’ collaborative practices to enhance school effectiveness and improvement in specific educational contexts.  相似文献   

非稳态雾赋能网络中的在线任务卸载方法     

朱兆伟  刘婷  钱骅  罗喜良 《中国科学院大学学报》2020,37(5):699-707

为充分发掘分布在不同位置上的雾节点的计算资源，任务卸载被寄予众望。在雾计算场景下，以尽可能减少任务卸载的长期成本为目标，试图寻找一个高效的在线任务卸载方法。为此，这一问题被建模成一个随机规划问题，该问题中系统参数所对应的随机变量的期望会在未知时刻突变，系统参数相关信息只能在任务完成后的反馈中获得。基于非稳态多臂老虎机模型，提出一个高效的算法来解决这一具有挑战性的随机优化问题，给出理论分析证明该算法的渐进最优性。数值实验证明了该算法的优越性。  相似文献   

制造企业服务化现状的影响因素检验          下载免费PDF全文

肖挺  黄先明 《科研管理》2018,39(2):108-116

我国制造企业正逐步从纯产品制造向专项提供“产品+服务”的组合，即进行服务化创新。本文通过对东中部若干省样本企业的调查研究分析影响企业服务化的因素，研究表明企业规模与服务化程度之间存在“倒U型”的关系，中等规模的企业最倾向于选择高度服务化。此外，服务化也和企业产品的工艺性、复杂性正相关，而企业创新能力越强则企业涉足服务化程度越深入，地区差异并不会对服务化水平产生实质性的影响，研究指出企业以及社会各界应当如技术创新一样重视服务化的作用。  相似文献   

Complex phonological tasks predict reading in 7 to 11 years of age typically developing Russian children     

Svetlana V. Dorofeeva  Anna Laurinavichyute  Victoria Reshetnikova  Tatyana V. Akhutina  Wim Tops  Olga Dragoy 《Journal of Research in Reading》2020,43(4):516-535

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