划水板流体动力特征的风洞实验研究

本文介绍了自行研制的三种划水板和国外两种划水板及其在风洞内进行的测力实验,以了解分析其不同的流体动力特征;对板面开孔与无孔吹风测力、板面有或无稳流板条及板条分布的测试结果,为新型划水板的设计提供了理论依据。研究发现,螺旋曲面扭转结构的自制板对运动员手掌最佳对水倾斜角有诱导修正作用,能帮助运动员建立良好的技术,提高“水感”,获得理想的划水效果。实验结果表明以上观点是可以肯定的。     

The Ephemeral,the Essential and the Material in the Conservation of Contemporary Art: Decision-Making for the Conservation of a Work of Art Made with Butterfly Wings

This article presents the intervention process carried out on a work of art created by artist Yolanda Gutiérrez Acosta, using a series of ephemeral materials such as butterfly wings and agave thorns. The work, an installation from 2002, is entitled ‘Efímeras’ (‘Ephemera’) and consists of 12 flowers mounted on acetate sheets and attached to the same with vinyl acetate copolymers and acrylic acid esters (Mowilith®). These flowers are installed on the floor in a bed of dried flowers. The conservation of contemporary art can lead to some previously unimaginable problems for restorers. Current works of art are somewhat material in nature, but they also have a conceptual dimension that is essential for their artistic interpretation. The artist’s participation in the decision-making process prior to the restoration was quite useful. The passage of time, its effect on the work, and the need to understand the possibility of the demise and destruction of the work were implicit as of the onset of its creation, such that, according to the artist, we are forced to reflect upon the possibilities of its future state.     

Ultrabithorax is a key regulator for the dimorphism of wings,a main cause for the outbreak of planthoppers in rice

Rice planthoppers, the most devastating rice pests, occur in two wing forms: the short-wing form for rapid population growth and long-wing form for long-distance migration, which together create the mechanism for outbreak. Here we show that Ultrabithorax (Ubx) is a key regulator for switching between the long- and short-wing forms of rice planthoppers. Ubx is expressed in both forewing and hindwing pads, which is different from the canonical model of Ubx expression. In brown planthoppers, expression of Ubx (NlUbx) is regulated by nutritional status of the rice host. High-quality young plants induce NlUbx expression leading to the short-wing form; low-quality ripe plants reduce NlUbx expression resulting in long-wing form. We also showed that NlUbx is regulated by the insulin receptors NlInR1 and NlInR2. The default expression of NlInR1 inhibits NlUbx resulting in long-wings, while high-quality hosts induce NlInR2 expression, which represses NlInR1 thus promoting NlUbx expression to produce short-wings.     

Historicising teachers’ learning: a case study of productive professional practice

This paper reveals the significant historical traces which informed the learning practices of teachers at one particular school site in a rural and regional educational district in Australia. Drawing upon recent theorising into professional practice, the paper argues that teacher learning practices are intrinsically ‘ecologically’ related to teachers’ practices at specific sites. However, extending beyond this theorising, the research also reveals how teacher learning – in the case presented, in relation to classroom dialogue – is also significantly influenced by earlier learning experiences of the teachers involved. In this way, teachers’ practices are revealed as not only influenced by present-day, site-specific, whole-school teacher learning, but also by particular events encountered by teachers at an earlier phase of their careers. The research argues for a conception of teachers’ learning which is not only site-informed and ecologically arranged, but also deeply temporally embedded.     

基于单向流固耦合的不同风速下帆板帆翼空气动力性能仿真

目的：探究不同风速对帆板帆翼结构以及周围流场的影响。方法：以奥运女子级别的Neil Pryde RS：X帆板帆翼为研究对象,考虑空气动力与结构的流固耦合效应,利用ANSYS Workbench进行单向流固耦合分析。结果：Realizable模型适合计算帆翼周围的流场湍流度,在风速为2m/s时帆翼升阻比最大;随着风速的增大,帆翼面发生变形和振动会导致风激振现象、背风面产生明显的涡脱现象,且帆翼表面应力区增大,全帆的应变逐步增加。结论：不同风速下的帆翼迎风面和背风面的压力分布、帆翼整体空气动力有一定差异,运动员比赛中应该根据当时风况调整帆翼参数。     

蒋丞稷26届奥运会100m蝶泳各阶段技术分析

对蒋丞稷100m蝶泳出发、途中游、转身、冲刺各阶段技术进行分析,并与国内外优秀选手比較显示,蒋丞稷出发反应时和出发15m技术达到世界先进水平;途中游划幅较大,划频较低;转身前7.5m较25-50m游速减慢0.03米/秒,这是蒋丞稷100m蝶泳技术中较为薄弱环节;终点冲刺没有明显减速,但其冲刺前加速游能力还不如国內外优秀选手,有待进一步提高。     

左翼文化运动中的"革命文学"之争

二十世纪二十年代末到三十年代,国家内忧外患,国民党进行文化“围剿”。面对这种景象,在文化界掀起了左翼文化运动,这是继五四运动之后又一次思想文化的解放。在这次运动中,以宣传革命文学为主,又对革命文学进行了激烈的论争,指引宣传走向正确的方向。     

蝴蝶不同部位提取DNA效果的研究

提取高质量的蝴蝶基因组是蝶类分子系统学研究的重要步骤。本文通过对蝴蝶干标本不同部位DNA提取效果的比较,找出了最适合蝴蝶干标本基因组DNA提取的部位,同时用PCR扩增的方法进行了检验,力争为开展蝴蝶的分子生物学研究奠定基础。结果表明,足部的提取效果最佳。     

“诗”“歌”中蝴蝶意象研究

蝴蝶是诗词中常见的一种意象,多用来表达自由闲适、爱情新生、美丽感伤等主题。文章探讨古典诗词中的蝴蝶意象,通过对蝴蝶意象的阐释来把握诗人对世界独特的理解,以及特定时代诗歌的某种整体经验。     

蜻蜓拍翼前飞中模型翼动态柔性变形的气动效应研究

根据蜻蜓拍翼前飞激发的流场具有St>>1/Re的特点，在理论模化框架下，本文采用势流假设，用二维变形体前、后缘脱涡的面元法研究了前飞模型蜻蜓翼在周期性拍动中动态柔性变形引起的气动力响应。通过比较柔性模型翼和刚性模型翼气动力随时间的变化，发现在下拍行程中动态柔性变形显著地提高了升力和推力；值得注意的是，蜻蜓前飞时，翼的实际柔性变形幅值恰处于一个最佳范围内，它大幅地提高了升力，同时使消耗的气动功率趋近于最低，有利于蜻蜓维持前飞状态。