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   

高校图书馆微信公众平台老年教师使用意愿影响因素研究     

王征  刘帅 《图书情报工作》2019,63(6):41-48

[目的/意义]老年教师的使用意愿不高严重影响了高校图书馆微信公众平台的发展与进步，因此需要研究高校图书馆微信公众平台的老年教师使用意愿影响因素。[方法/过程]对科技接受模型进行改进与扩展，基于结构方程，引入性别、年龄与经验等调节因素，搭建老年教师高校图书馆微信公众平台使用意愿模型，并基于四川高校的调研数据对模型与假设进行检验与分析。[结果/结论]研究结果表明：从整体来看，该模型对老年教师高校图书馆微信公众号使用意愿的总体解释效果良好；从各个影响因素来看：实用性感知以及群体影响对老年教师高校图书馆微信公众号使用意愿具有显著的正面影响，而生理机能显著反向影响其使用意愿。  相似文献   

离散制造智能化关键技术协同创新及影响因素研究     

孟凡生  马茹浩 《科研管理》2023,44(1):37-47

数字经济下智能化关键技术创新是离散制造企业向智能化转型的必然要求。本文基于离散制造特点与智能化技术应用，首先从需求设计、生产管理、信息管理和知识管理四个方面制定离散制造企业的智能化方案，并构建离散制造的智能化关键技术协同创新体系。其次以中国23个离散型智能制造企业为研究对象，建立智能化关键技术协同创新影响因素指标体系，并用熵权法和灰色关联分析法进行实证研究。实证结果表明：企业创新能力、企业智造潜力、企业协同动力、区域创新能力和外部环境支持对智能化关键技术协同创新起促进作用；在二级指标中，企业知识存量与政府补贴是智能化关键技术协同创新的主要影响因素。  相似文献   

Factors influencing the career interest of SENCOs in English schools     

Graeme Dobson  Graeme Douglas 《British Educational Research Journal》2020,46(6):1256-1278

A named professional with responsibility for overseeing and coordinating the educational inclusion of pupils with special educational needs and disabilities has become an important school role in many countries. In England, the SENCO (special educational needs coordinator) became a mandatory role in 1994, and associated mandatory training was introduced in 2009. A questionnaire survey of 618 in-training and actual SENCOs revealed that their motivating interest in becoming a SENCO varied. An exploratory factor analysis of 32 items covering different interests in the role yielded four interest factors in becoming a SENCO: outward-facing factors (‘inclusion’ and ‘high-quality provision’) and inward-facing factors (‘educational and professional development’ and ‘leadership voice and status’). The outward-facing factors were viewed as more important to respondents than the inward-facing factors. Interest factors did not interact with organisational variables, including age group taught and school quality. Nevertheless, younger SENCOs and those engaged in training were more motivated by educational and professional development. SENCOs holding school leadership contracts were more motivated in developing leadership voice and status compared with their classroom teacher peers. Moreover, there was a significant overall difference with women reporting a higher interest than men across all factors.  相似文献   

高校图书馆参与公共文化服务体系影响因素研究     

曹国凤  贾晓彦  张丽 《图书情报工作》2019,63(6):35-40

[目的/意义]构建高校图书馆参与公共文化服务体系影响因素模型，为高校图书馆公共文化服务发展提供理论和实践参考。[方法/过程]通过对10所高校26位采访对象的深度访谈，采用扎根理论方法，探索性研究高校图书馆参与公共文化服务体系影响因素，并构建其扎根理论模型。[结果/结论]高校图书馆参与公共文化服务体系影响因素主要包括4个主范畴：高校及其图书馆归因、政府机构归因、公众用户归因、其他归因。其中高校及其图书馆归因是主导性因素，政府机构归因是保障性因素，公众用户归因是驱动性因素，其他归因是制约性因素。在此基础上，提出高校图书馆深度参与公共文化服务体系策略。  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   

低负荷加压训练改善自发性高血压大鼠的血压效果及机制研究     

谭朝文  赵彦  俞莹莹  马晓缓  郑玉婵 《体育科学》2020,(3):46-53,63

目的:探究低负荷加压训练对自发性高血压大鼠的降压效果及其作用机制。方法:选取4周龄雄性自发性高血压大鼠,随机分为对照组(高血压安静组)、低负荷训练组、低负荷加压训练组和高负荷训练组。低负荷训练组进行35%~55%1RM递进式低负荷爬梯训练,低负荷加压训练组进行30%~40%血流受限结合35%~55%1RM递进式低负荷爬梯训练,高负荷训练组进行55%~75%1RM递进式高负荷爬梯训练,训练后测定血压、血液中内皮素-1、血管内皮生长因子、一氧化氮合成酶的表达和心肌组织中内皮型一氧化氮合成酶的表达。结果:1)与对照组、高负荷训练组相比,低负荷加压训练组收缩压、舒张压显著下降(P<0.05);与低负荷训练组相比,低负荷加压训练组舒张压显著下降(P<0.05)。2)与对照组相比,低负荷加压训练组血液中内皮素-1表达显著下调(P<0.05),血管内皮生长因子和一氧化氮合成酶表达显著上调(P<0.05);3)与对照组相比,低负荷加压训练组心肌中内皮型一氧化氮合成酶表达显著上调(P<0.05);4)在低负荷加压训练组中,收缩压与内皮素-1呈正相关,相关性分析具有统计学意义(P<0.05);收缩压与一氧化氮合成酶、血管内皮生长因子、内皮型一氧化氮合成酶均呈负相关,相关性分析具有统计学意义(P<0.05)。结论:1)低负荷加压训练降压效果优于高负荷训练;2)低负荷加压训练能够通过下调血液中内皮素-1的表达,上调血液中血管内皮生长因子和一氧化氮合成酶的表达,同时上调心肌中内皮型一氧化氮合成酶表达,改善内皮细胞功能,达到降压的效果。  相似文献   

Response of brain-derived neurotrophic factor to combining cognitive and physical exercise     

Toshiaki Miyamoto  Saya Hashimoto  Hideya Yanamoto  Mai Ikawa  Yoshiki Nakano  Takashi Sekiyama 《European Journal of Sport Science》2018,18(8):1119-1127

Purpose: Brain-derived neurotrophic factor (BDNF) is well known for its potential to promote brain plasticity. It has been proposed that combining cognitive and physical exercise (CCPE) may have the potential to generate more synergistic benefits in cognitive function than either cognitive exercise (CE) or physical exercise (PE) alone. The purpose of this study was to examine acute responses of peripheral BDNF levels and cognitive performance to CE, PE, and CCPE.

Methods: Thirteen healthy adult men participated in four experimental sessions; a 30-min CE, a 30-min cycling PE at an intensity of 60% peak oxygen uptake, a 30-min CCPE at the same intensity as PE, and a 30-min session of complete rest. Plasma BDNF levels and cognitive performance were measured before and after each session.

Results: Both PE and CCPE significantly increased plasma BDNF levels (p?p?≥?.05), and there was no significant difference in peripheral BDNF levels between PE and CCPE (p?≥?.05). No session induced a significant change in cognitive performance (p?≥?.05).

Conclusions: Our study suggests that CE and PE have different responses of peripheral BDNF levels and that CCPE had no additional or synergistic effect on peripheral BDNF levels compared with PE alone. This study offers further insights into the potential mechanisms underlying the respective roles of CE, PE, and CCPE for peripheral BDNF levels and cognitive performance.  相似文献   

Factorial and convergent validity of the Exercise Identity Scale in a German adult sample     

Fabienne Ennigkeit  Frank Hänsel 《Measurement in physical education and exercise science》2018,22(4):343-355

The purpose of the present study was to examine the factorial and convergent validity of the German translation of the Exercise Identity Scale (EIS; Anderson & Cychosz, 1994). We introduce a bifactor model as a possible alternative to the previously discussed one- and two-factor models. Using an online study with 530 participants, our results suggest that the EIS should be considered a unidimensional measure. For this one-factor model, temporal invariance (time interval: 2 weeks) and invariance between men and women could be established. Relations to similar constructs were in the expected directions. We provide a psychometrically sound German version of the EIS, which demonstrated factorial and convergent validity in this study. The use of the scale in German samples is likely to advance research on exercise adoption and maintenance by integrating the exercise identity construct.  相似文献