纳米流体液滴撞击固体壁面的实验和模拟研究     

王睿  沈学峰  霍元平  王军锋  郑诺  刘海龙 《中国科学院大学学报》2020,37(2):281-287

液滴撞击固体壁面现象常见于动力机械、喷雾冷却和薄膜材料沉积制备等工业生产中。将石墨烯和碳纳米管作为分散颗粒，应用超声波分散技术制备均匀性与稳定性良好的树脂基纳米流体。利用高速摄像技术，研究纳米流体液滴撞击固体壁面的动力学行为。基于有限元法，通过修正的幂律黏度模型耦合纳米流体的剪切变稀特性，采用水平集方法捕捉相界面的移动，建立纳米流体液滴撞击固体壁面的数值模型。模拟结果与实验结果较好一致，验证了数值模型的正确性与准确性。研究发现实验配制的纳米流体表现出非牛顿剪切变稀特性，纳米颗粒的加入抑制了液滴撞击固体壁面过程中的铺展和回缩行为。随着幂律指数m的减小，液滴撞击固体壁面后的铺展范围变大。随着表面张力的增大，液滴的无量纲直径在铺展阶段无明显变化，但在回缩阶段逐渐减小。  相似文献   

基于社会资本理论的社交问答用户健康信息行为研究     

陆泉  刘婷  邓胜利 《图书情报工作》2019,63(17):118-127

[目的/意义]社交问答用户的社会资本受多种因素影响，本文旨在探究社交问答用户不同的健康信息行为对其社会资本积累的影响。[方法/过程]以知乎网上糖尿病话题下2 537个问题帖子，3 567个回答的1 650名用户为研究对象，依据L.Nan的社会资本理论和N.Uphoff对社会资本的分类，将社交问答用户的社会资本分为认知性和结构性两类，用多元线性回归的方法分析社会问答用户的健康信息行为与社会资本之间的关系。[结果/结论]用户的健康知识贡献行为和自我信息披露行为在不同程度上正向促进社会资本的累积，而不同的健康知识获取行为对认知性社会资本和结构性社会资本的影响有差异。这些结果有助于社交问答用户提高社会资本，平台完善用户服务和激励机制。  相似文献   

工作资源对高校图书馆员敬业度影响机制的实证研究     

康超群  杨晴 《图书情报工作》2019,63(17):69-76

[目的/意义]探讨工作资源对高校图书馆员敬业度的影响与机制，以期为高校图书馆实施人力资源管理和提升图书馆员的敬业度提供参考。[方法/过程]选取湖南各高校图书馆的358名馆员为研究对象，考察工作资源对高校图书馆员敬业度的预测作用以及心理资本与组织承诺在两者之间的中介作用。[结果/结论]描述性统计与差异分析、相关分析和逐步回归分析的结果表明，不同性别的高校图书馆员在组织承诺量表得分上存在显著性差异，男性馆员组织承诺得分显著高于女性，不同性别馆员在其余得分上均不存在显著性差异。不同婚姻、年龄、学历、职位、职称者在各量表得分上均不存在显著性差异。高校图书馆员工作资源、心理资本、组织承诺与敬业度的两两相关都达到统计显著性水平。工作资源对高校图书馆员的敬业度具有正向预测作用，心理资本和组织承诺能够在工作资源对高校图书馆员敬业度的影响中起部分中介作用。丰富高校图书馆员工作资源，增进其组织支持感，增强其心理资本和组织承诺，是促进高校图书馆员敬业度提升的有效路径。  相似文献   

新冠肺炎后演艺行业的走势     

姚石 《演艺科技》2020,(3):1-3

2020年,演艺行业虽受新冠肺炎疫情影响,但需求始终存在,并能够随着经济的增长而增长。5G、大数据中心、人工智能和工业互联的发展,将推动演艺行业在在线化、专业音视频与消费类产品融合发展。  相似文献   

Kinetic and kinematic analysis of stamping impacts during simulated rucking in rugby union     

Bodil Y Oudshoorn  Heather F Driscoll  Marcus Dunn  David James 《Journal of sports sciences》2018,36(8):914-919

Laceration injuries account for up to 23% of injuries in rugby union. They are frequently caused by studded footwear as a result of a player stamping onto another player during the ruck. Little is known about the kinetics and kinematics of rugby stamping impacts; current test methods assessing laceration injury risk of stud designs therefore lack informed test parameters. In this study, twelve participants stamped on an anthropomorphic test device in a one-on-one simulated ruck setting. Velocity and inclination angle of the foot prior to impact was determined from high-speed video footage. Total stamping force and individual stud force were measured using pressure sensors. Mean foot inbound velocity was 4.3 m ? s^?1 (range 2.1–6.3 m ? s^?1). Mean peak total force was 1246 N and mean peak stud force was 214 N. The total mean effective mass during stamping was 6.6 kg (range: 1.6–13.5 kg) and stud effective mass was 1.2 kg (range: 0.5–2.9 kg). These results provide representative test parameters for mechanical test devices designed to assess laceration injury risk of studded footwear for rugby union.  相似文献   

我国SCI收录期刊影响因子相关自被引率的国际比较     

盛丽娜 《中国科技期刊研究》2018,29(1):69-74

【目的】 分析我国SCI收录期刊影响因子相关自被引率(SCR-IF)的状况，进一步解读自引在影响因子中的作用，以利于我国办刊人掌握期刊的发展方向。【方法】 以2015年版SCI收录期刊为研究对象，计算中国和G7国家(美国、英国、德国、法国、日本、意大利、加拿大)、有代表性的新兴国家(韩国、印度、俄罗斯)期刊自被引率(SCR)，同时计算各刊的SCR-IF、非影响因子相关自被引率(SCR-NIF)及二者比值K，对各国期刊的SCR-IF、SCR-NIF、SCR、K值情况进行对比分析。【结果】 各国期刊SCR-IF的均值均大于SCR-NIF和SCR，K的中位值为1.502~1.889；我国SCI收录期刊的SCR-IF、SCR-NIF均小于韩国和俄罗斯，但高于其他8个国家；我国SCI收录期刊中，SCR-IF为0的期刊占比为3.28%，小于各国均值6.21%；我国K>2.0的期刊占比为34.97%，小于各国均值37.19%。【结论】 SCR-IF较SCR更能准确反映期刊自引对影响因子的实际作用。我国SCI收录期刊SCR-IF相对较高，但仍有部分期刊的自引对影响因子没有任何作用，且我国SCI收录期刊的自引较少有人为操控。  相似文献   

The impact of development education and education for sustainable development interventions: a synthesis of the research     

J. O’Flaherty  M. Liddy 《Environmental Education Research》2018,24(7):1031-1049

The Sustainable Development Goals set out by the United Nations advocate that all learners will have the knowledge and skills needed to promote sustainable development. Development education, education for sustainable development and global citizenship education are deliberate educational interventions, which all address global justice and sustainability issues. Current research continues to expand our understanding of the field, but there are no recent reviews of the literature addressing the impact of these educational interventions. The objective of this paper is, therefore, to examine the impact of intentional development education, education for sustainable development and global citizenship education. We reviewed 243 abstracts against specific inclusion criteria: 127 from Scopus, 101 from ERIC, and 15 from EBSCO. Of those abstracts, 99 met inclusion criteria and underwent double review, which excluded further studies. Of the final 44 papers included for review, 26 focused on education for sustainable development or environmental educational themes, 12 were global orientated in content, either through development education or global citizenship, and six were intercultural educational interventions. In this paper, we provide an overview of measures of assessment of learning used, review the evidence of the impact on learners, and address some methodological and pedagogical questions arising from the review.  相似文献   

Impacts of higher education quality accreditation: a case study in Vietnam     

Huong Thi Pham 《Quality in Higher Education》2018,24(2):168-185

Quality accreditation in higher education exists in many countries, including Vietnam. As of May 2018, 80 higher education institutions in Vietnam have officially been evaluated and recognised using the national quality standards. This study examined the impact of institutional accreditation on the evaluated university. The qualitative research evaluates the impact of external quality assurance from the perspective of managers of the university. The self-assessment phase helped the university assemble evidence of activities carried out at the university and the status of being recognised was believed to increase its prestige. The process, on the other hand, was also believed to be burdensome, time and cost consuming, which led to no significant changes at the institution. Lack of institutional autonomy and competence of the review team were barriers to any attempts to improve quality of higher education in Vietnam.  相似文献   

Teacher evaluation in Chile: highlights and complexities in 13 years of experience     

Beatrice Avalos-Bevan 《Teachers and Teaching》2018,24(3):297-311

The paper examines the process of establishing a teacher evaluation system in Chile and its acceptance by teachers over time. The conceptual base upon which the system was established is described. Evidence is also examined from a variety of data sources and research related to the evaluation system as well as teachers’ use of its results. This evidence includes information from an external review of the system noting tensions between the formative versus accountability purposes of the evaluation system and that are being attended to in the new Teacher Professional Development Law (2016).  相似文献   

微信公众号对提升英文科技期刊影响力的影响——以“药学学报”微信公众号为例     

周心玉  郭焕芳  郑爱莲 《中国科技期刊研究》2018,29(11):1171-1176

【目的】 探讨我国英文科技期刊微信公众号运营的思路，以提升我国英文科技期刊影响力。【方法】 采取个案研究法，总结我国英文科技期刊微信公众号的设计策略。【结果】 “药学学报”微信公众号通过宣传推广文章和构建期刊社群，成功地辅助《药学学报(英文版)》全面提升了影响力。【结论】 我国英文科技期刊微信公众号可围绕宣传期刊文章，以及运营由作者、编委、读者构成的期刊社群，以宣传期刊品牌，全面提升期刊影响力。  相似文献