Application of theoretical principles to swimsuit drag reduction

This study investigated the basic fluid mechanics associated with the hydrodynamic drag of a human. The components of drag (frictionD _SF, pressureD _P and waveD _W) on a human swimmer were analysed by applying classical fluid dynamic fundamentals. General methods of reducing drag were considered and the most probable method identified, applied and tested on swimsuit hydrodynamic drag. This study employed turbulators, either one (upper back) or three (across the upper back, the chest and across the buttocks), that were compared to an identical full body suit with no turbulators. Male and female elite competitive swimmers (n = 7 each) were towed in an annular pool to determine passive drag at speeds from 0.4 to 2.2 m s⁻¹. The total drag was reduced by 11–12% by one turbulator and 13–16% by three turbulators. The total drag was decomposed intoD _SF, D_P andD _W to determine the mechanisms responsible for the reduced total drag by the turbulators. The presence of the turbulators did not significantly increase friction or wave drag; however, flow was attached to the body as there was a significant reduction in pressure drag (19–41%), with the greatest reduction being for three turbulators (chest, back, buttocks). This study demonstrated the importance of pressure drag in determining total drag at high human swimming speeds, and that drag reducing technology can significantly reduce it, in this case by appropriately sized and placed turbulators.     

汉代墓葬中车马出行图像的类型分析

车马出行是两汉墓葬艺术中一个普遍而又重要的题材,对其意义的释读是该题材研究的重点,以往研究多依靠文献来解释图像,本文拟从图像本身出发,区分其不同的图式类型,并讨论各类型之间的关系,以此为线索思考该题材在墓葬中的意义。     

论发展中国“红色旅游”

通过发展红色旅游,有效保护和利用革命历史文化遗产,使老区的旅游品牌和形象更加鲜明,更好地整合自然环境资源和人文历史资源。实现"红""绿"结合,优势互补,发挥旅游业的关联带动作用,推进经济结构调整,促进生态建设和环境保护,扩大就业,增加收入,推动老区经济社会的协调发展。     

Report on Travel to Former Yugoslavia,April 17–May 7, 2008

The author traveled primarily to Sarajevo, Bosnia‐Herzegovina and Skopje, Macedonia. She attended the 4th International Convention of Slavicist Librarians in Sarajevo and visited the Sarajevo Book Fair. In both capitals she met with book vendors and visited bookstores and libraries. She also learned that travel between the successor states is more complicated now than before the breakup of close Yugoslavia.     

指掌步履之间──香港文学资料搜集及作品赏览

"指掌步履之间——香港文学资料搜集及作品赏览"是结合信息检索、文学作品和实地考察的推广阅读活动。本文简述这项活动的宗旨、概况及成效,藉此分享推广阅读的新模式。     

茂名热电厂#5机组一次风机多次跳闸导致轴承损坏分析

一次风机是燃煤机组的重要组成部分,一次风机出现故障将严重危及机组的安全运行,限制机组负荷出力,不仅给厂带来经济效益的损失,同时对外界负荷需求造成不必要的影响,该厂一次风机从初次投运至今已发生10余次风机轴承损坏事故,不仅给运行、检修人员带来严重的心理压力,同时给厂带来严重的给经济损失。通过分析对比一次风机多次跳闸事故,完善一次风机运行环境及逻辑运行,提高一次风机运行的可靠系数,减少运行、检修人员压力,从而提高机组的安全运行的稳定性。     

Reflective Practice as a Means for Preparing to Teach Outdoors in an Ecological Garden

Although teachers are engaged in many field-trips, they seldom have the pedagogical knowledge and experience to enact them. This article presents an effort to support reflective practice of teachers in the outdoors. The teaching experience of five pre- and in-service teachers included preparation for teaching in the outdoors, designing learning materials, teaching elementary and junior-high school students in an ecogarden, and reflecting upon these teaching experiences. The data collected by teachers and researchers highlighted challenges such as lack of confidence, class management and inadequate student motivation. The group and the instructors’ support and collaboration and careful preparation yielded a positive outdoor teaching experience. We suggest that supported field experience followed by individual and group reflection are promising in encouraging teachers to carry out outdoor learning activities.     

除氧器虚假水位引发机组跳闸的原因分析及防范措施

分析了600MW超临界机组除氧器虚假水位误发信号引发跳机事故的原因、处理过程及防范措施,为同行技术人员防范同类故障提供参考。     

交通方式划分的非集计模型——以蚌埠为例

为研究影响城市交通结构的主要因素,建立出行者属性与个体出行方式选择的合理关系模型.所有的出行者相关属性数据均由统计资料获得,方式选择数据由蚌埠市居民出行调查的数据获得.应用非集计模型来建立个人属性、家庭属性和出行属性与方式选择间的函数关系.建模结果表明：居民出行交通方式选择与个人属性、家庭属性和出行属性之间有较稳定的关系,其随着时间的推移变化甚微.非集计模型所推算的交通方式结构较为精确,可用于交通方式结构的预测.此外,所建模型亦能识别方式分担的主要影响因素,从而实现交通方式结构优化.