叶片数量对小型垂直轴风机气动性能的影响分析     

樊百林  王俊朋  尉国梁  崔嘉萌  王宏伟  金松吉 《科技通报》2021,37(5):58-63

叶片数量是影响风机气动性能重要因素之一,本文从力矩和来风速度两个角度来分析叶片数对风机气动性能的影响,利用CFD工具对叶片数和气动性能的关系进行了分析,首先利用滑移网格技术,对风机进行两个周期流场二维模拟分析,比较了在不同工况下,三叶片和四叶片在不同方位角产生的瞬时合力矩;其次基于数值模拟出来的平均力矩,做出不同来风速度下,Cp(风能利用率)和λ(尖速比)的曲线图,最后再根据双流管理论做出的Cp和λ的曲线图做对比,说明了模拟结果的可靠性,对风机在不同工况下叶片数量的选择有一定的参考意义.  相似文献   

Aiding education in conflict: The role of international education providers operating in Afghanistan and Pakistan     

Adele Harmer  Abby Stoddard  Victoria DiDomenico 《Prospects》2011,41(2):205-221

Amid rising violence against civilian aid operations in insecure environments, attacks on the education sector pose a unique set of challenges for international aid actors. In recent years incidents of violence targeting the education sector in Afghanistan and the conflict-affected areas of Pakistan have increased. This article synthesizes recent research, quantitative analyses, and observations of practitioners in order to explore the key issues facing aid workers in the education sector. The findings suggest that in extremely violent and polarized environments such as Afghanistan and the conflict-affected areas of Pakistan, the international community can provide education assistance more effectively and securely through a low-profile, community-based approach that de-emphasizes the role of government, and avoids, as far as possible, any association with international political/military actors. The authors conclude that education sector coordinators could play a larger role in providing practical guidance and supporting an inter-agency dialogue to share lessons and good practice in delivering education services in these contexts.  相似文献   

Low Cost but Effective: Staff Development Activities in Community College Student Affairs     

Noelle A. Mecoli  Nikkia Gumbs  Vicki Ward  Abby Willcox 《Community College Journal of Research & Practice》2019,43(1):70-73

This study examines staff development practices in community college student affairs. Nineteen interviews were conducted with supervisors in a variety of departments at community colleges. We found that supervisors frequently used multiple practices such as conducting staff meetings, attending institutional training, or viewing topical webinars were frequently used by supervisors to provide professional development opportunities. We also highlight distinct approaches including the concept of active listening and after-hours activities. Finally, we explore implications for staff development in community colleges and identify potential future practices and improvements.  相似文献   

快速城镇化进程中不同类型农户弃耕特点及原因——基于重庆市十区县540 户农户调查   总被引：17，自引：1，他引：16  

张佰林  杨庆媛  严燕  薛梅  苏康传  臧波 《资源科学》2011,33(11):2047-2054

运用参与式农村评估法、Logistic分析法,基于农户兼业活动探讨不同类型农户弃耕特点及原因,为破解生态脆弱的贫困地区农地资源低效利用问题提供参考。结果表明：①重庆市农户兼业普遍,根据非农收入比重、劳动力配置状况和生计策略,将农户划分为纯农户、I兼农户和II兼农户;②农户耕地转出行为普遍,无偿转出比重偏高。II兼农户弃耕及有偿转出比重均最高,与I兼衣户相比,纯农户耕地转出的户数多,但转出面积少且多为无偿转出;旱地撂荒较水田普遍,撂荒的多为地块破碎、耕作条件差的地块;③由于家庭成员年龄偏老、劳动能力偏弱等的局限,纯农户会放弃对区位偏远、零星分散地块的耕种;I兼农户更关注土地经济收益,将资本投入到耕作条件好的地块;II兼农户主要基于收益最大化原则,倾向于将要素投入到非农产业,有偿转出耕地。研究认为,根据不同类型农户弃耕特点及原因制定相应政策措施来引导其土地利用行为,是整合区域土地资源、提高农地利用效率的有效途径。  相似文献   

An Initial Investigation into Naturally Occurring Loss- and Gain-Framed Memorable Breast Cancer Messages     

Laplante C  Smith S  Kotowski M  Nazione S  Stohl C  Prestin A  So J  Nabi R 《Communication quarterly》2012,60(1):1-16

Memorable message research examines interpersonal messages "…remembered for extremely long periods of time and which people perceive as a major influence on the course of their lives" (Knapp, Stohl, & Reardon, 1981, p. 27). They can also guide actions, such as health behaviors. This exploratory research examined self-reported memorable messages about breast cancer to determine if they were framed, emphasizing either the benefits (gain-framed) or the costs (loss-framed) of a behavior. About one-fourth of the messages were framed, with most being gain-framed. The messages tended to emphasize early detection actions. Study limitations and implications for future research are discussed.  相似文献   

基于云架构的连续数据保护技术在烟草制造企业中的应用探索     

潘佰林  汪炎平  李寒曦  金振训 《科技通报》2014,(11)

结合云计算技术与烟草制造企业的生产数据保护要求,就烟草制造企业的数据安全保护技术做了理论研究和应用建设探索,指出了烟草制造企业中连续数据保护技术的重要性及实现方法,为今后行业内提升企业数据安全提供理论指导。  相似文献   

On originality     

Sharon Bailin 《Interchange》1985,16(1):6-13

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高等教育保障体系数字图书馆浅析——从数字图书馆四要素角度     

丘柏林 《图书馆学研究》2007,(5):20-22

本文从数字图书馆的四要素：数字资源建设、数字资源的长期保存、数字资源的发布与服务以及数字图书馆的科学管理方面分析高等教育保障体系数字图书馆。  相似文献   

Critical Thinking and Science Education   总被引：1，自引：0，他引：1  

Sharon Bailin 《Science & Education》2002,11(4):361-375

It is widely held that developing critical thinking is one of thegoals of science education. Although there is much valuable work in the area, the field lacksa coherent and defensible conception of critical thinking. As a result, many efforts to foster criticalthinking in science rest on misconceptions about the nature of critical thinking. This paper examines some of themisconceptions, in particular the characterization of critical thinking in terms of processes orskills and the separation of critical thinking and knowledge. It offers a more philosophically sound and justifiableconception of critical thinking, and demonstrates how this conception could be used to ground scienceeducation practice.  相似文献   

Comment     

Sharon Bailin 《Interchange》1986,17(2):54-56

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