Experimental Investigation with PIV on Characteristics of Shedding Vortices in Wake of Flapping Wings

通过色流实验和粒子成像测速技术（particle image velocimetry,PIV）对扑翼近场尾流脱落涡的结构轨迹和能量进行了定性及定量研究.结果表明：因展向流动充分性的不同,存在两种牛角型涡系结构;上下扑时翅翼交替产生顺时针和逆时针脱落涡,两涡运动轨迹呈近似弧形对称,对称轴的仰角略大于攻角;脱落涡的涡心涡量在上下扑极点达到最大值,环量最大值出现在到达极点前的1/5~2/5周期之间;产生脱落涡的半周期内,涡的平均环量都随减缩频率的增大而增大,减缩频率较低时,下扑平均环量大于上扑平均环量,减缩频率较高时则相反;振幅对涡能量影响明显,减缩频率为2~2.5时,振幅±40°时的涡平均环量约是振幅±30°时的两倍,减缩频率越大振幅影响越明显.Qualitative and quantitative studies on the vortices structure, motion path and energy in the near-f ield wake of flapping wings were conducted through dye-flow tests and particle image velocimetry （ PIV） in tank. Results indicate that two kinds of horn-shaped vortices structures exist during f lapping under insuf f icient or suf iicient spanwise flow. Ant iclock-wise and clockwise vortices arise alternately during downward and upward flapping, whose traces are approximately symmet-rical. The elevation angle of symmetry-axis is slight ly larger than the attack angle of flapping wings. The vort icity of vortex core reaches its maximum at the top or bottom point, while the maximum circulat ion occurs at 1/5 ~ 2/5 period before the top or bottom point. The average circulations of both vortices during half period of producing them ascend with the increase of reduced frequency. At small reduced frequency, the average circulat ion during downward f lapping is larger than that dur-ing upward flapping. Contrary result is observed in case of large reduced frequency. Flapping amplitude signif icant ly inf lu-ence the vortex intensities, e.g. when reduced frequency is 2-2.5, the average circulat ion of vortices with an amplitude of ±40° is about twice that of amplitude of ±30°,and the influence grows with the increase of reduced frequency

同轴旋转圆台环隙流动机制及实验研究

同轴旋转圆台环隙内流体的流动是基于经典的两同轴旋转圆柱环隙内泰勒库特流的一种扩展研究。通过流动显示实验和PIV粒子图像测速技术对圆台环隙的内部流场进行可视化和定量化的研究,分析涡运动的周期性规律,探究圆台环隙内雷诺应力分布和水位高度对流场的影响。研究表明,随着时间的发展,涡列周期性明显且整体在下移,当脉冲数为100脉冲/s时,环隙内形成均匀分布的正反交替的涡;当脉冲数为200~500脉冲/s时,存在快慢交替的分裂周期;在3种水位高度下也都存在明显周期性分裂,只是周期时间和涡的个数不同;平均流场存在上凸型外向流和下凹型内向流2种流态,流态的差异是离心力与静压力双重作用的强弱变化所致;雷诺应力分布中,径向正应力占主导,并主要集中在环隙中部。国家自然科学基金(11072206);;福建省自然科学基金(2012J01023)~

Damage to mangroves from extreme cold in early 2008 in southern China

通讯作者Author for correspondence (E-mail: [email protected])2008年初,我国南方19个省经历了50年一遇的持续低温雨雪冰冻天气。极端气候对华南沿海各省的红树林区造成不同程度的危害。2008年3月,在我国南方各省红树林区的10个代表性地点,对这次寒害造成的红树植物伤害程度进行了系统的调查。结果表明:冬季低温对红树林的影响极为显著,特别是在低纬度的海南、广西和广东湛江,由于极端低温正值夜间退潮,对红树林的影响更为显著;在纬度较高的福建,本地红树种类秋茄(Kandelia obovata)、桐花树(Aegiceras corniculatum)和白骨壤(Avicennia marina)及引种的木榄(Bruguiera gymnorrhiza)等,由于长期适应于冬季较低的气温或在种植前经过抗寒锻炼,具有较强的抗寒能力。各地主要红树植物中,广布种秋茄、桐花树和白骨壤最为耐寒,其耐寒性均大于红树科的木榄、海莲(Bruguiera sexangula)和红海榄(Rhizophora stylosa)。海桑(Sonneratia caseolaris)对温度的敏感性最强,抗寒能力最低,因此,即使在其原产地海南也受到较为严重的寒害,在纬度更高的引种地出现大面积受害甚至全部死亡,而从孟加拉国引种的无瓣海桑(Sonneratia apetala)却显示出一定的抗寒能力。同一地点的红树植物幼苗的抗寒能力低于大树。此次寒害也造成了苗圃场的种苗大量死亡,成熟的植株提前落花落果,这势必会影响后继一两年内红树林的自然更新和人工造林。因此,在未来红树林造林或人工引种中,一定要考虑到红树植物的抗寒能力。国家自然科学基金(30671646和30700092);厦门大学“闽江学者”启动基

Studies on Genetic Transformation of Narcissus tazetta L.var. chinensis Roem. by IPT Gene

中国水仙作为一种重要的观赏花卉，具有很高的经济价值；应用基因工程技术对中国水仙进行品质改良，有利于提高水仙的商品价值。本研究的目的是将自我调控延缓叶片衰老系统应用于中国水仙，转IPT基因在水仙体内表达后延缓叶片衰老，使水仙在光合性能及开花表现上有所改善；同时利用GUS基因的报告作用，建立和优化中国水仙的遗传转化体系，为今后水仙遗传改良的进一步研究奠定基础，主要结果如下： （1）建立了中国水仙的基因转化受体系统。一是鳞茎盘直接分化再生途径，含部分鳞片的鳞茎盘在MS+6-BA4+NAA0.5培养基上全部诱导出小鳞芽，诱导系数为11.2；二是愈伤组织再生途径，花梗在MS+6-BA1+NAA5培养基...Narcissus tazetta has great value as an important flower plant in China. The autolatory senescence inhibition system, constructed by fusing leaf senescence specific promoter with IPT gene, is applied to the transformation of narcissus in this experiment. IPT expression in the transgenic plant can delay leaf senescence by increasing endogerous cytokinin level. At the same time, we have in the first...学位：理学硕士院系专业：生命科学学院生物学系_细胞生物学学号：19982601

选择CO_2激光器输出谱线的一个简单方案

本文提出了一个用控制锗窗温度的办法实现CO_2激光器选频的简单方案。定量地讨论了锗窗温度变化对腔频的影响及所引起的其相干反射极大的频移,并结合介质增益分析了它们对激光输出谱线的影响。实验证实该选频方案是切实可行的

Experimental Study on Aircraft Carrier Air Wakes

航空母舰的空气尾流对舰载机的起飞、着舰有较大的影响,认清航母尾流对舰载机的干扰原因有助于提高舰载机起降的安全性.实验以辽宁舰航母的缩比模型为研究; 对象,在多功能循环水槽中研究其尾流结构.利用染色液流动显示技术和粒子成像测速技术显示和测量航母的尾流结构随航向角、流速和关键位置的变化.基于模型; 迎流宽度定义的雷诺数范围为$2 \times {10^4} \sim 4 \times; {10^4}$.研究表明,舰首滑跃甲板存在上洗气流且两侧产生流向涡,该涡结构对舰载机滑跃起飞时的升力产生影响;舰岛和舰尾后方存在着大量脱落涡,会; 对舰载机着舰时的气动力产生扰动,增加着舰操纵难度.Aircraft carrier air wake exerts a very important impact on the; carrier-based aircraft take-off and landing.Identify the disturbance of; the aircraft carrier wakes on the carrier-based aircraft will contribute; to improve the safety of the aircraft take-off and landing.Experiment; take Liaoning aircraft carrier shrinkage model as the research; object,which has similar geometry shape of the Liaoning aircraft; carrier,and research on the wake structure of the aircraft carrier model; in multifunctional water tunnel.Using the dyeing flow visualization; experiment and PIV measurement to measure the wake structure of aircraft; carrier model different with heading angles,velocity of flow and the key; positions.Based on the definition of the width of model,the scope of; Reynolds number is $2 \times {10^4} \sim 4 \times {10^4}$.Results show; that there are up washs on the ski jump deck and flow vortex on both; sides of the ski jump deck, which have an impact on the lift of; carrier-based aircraft.Besides,there are shedding vortices behind the; ship island and stern,which will interfere the aerodynamic force of; carrier-based aircraft and greatly increase the operating difficulty of; landing.国家自然科学基金; 福建省自然科学基

Establishment of Agrobacterium-mediatedTransformation of Narcissus tazetta

利用根癌农杆菌介导法将 GUS基因导入中国水仙 ,组织化学法检测转化后共培养 3d的水仙鳞茎盘组织块 ,GUS基因瞬时表达很好 ,90 %以上的材料呈现大面积的蓝色斑块 ,取筛选培养 2 0d的材料检测 GU S基因的稳定表达 ,约 1%的组织块有蓝色反应 .水仙预培养 10 d后转化 ,转化前在菌液中加入 60 μmol/ L AS活化 2～ 3h,转化率提高了两倍以上 .转化材料在 MS+ BA10 + NAA0 .2+ Cef30 0 + Hyg30 培养基上培养 2 0 d左右分化出小鳞芽 ,频率约为 60 % ,组织块平均出芽 5 .7个 ,最多可达 14个 ,小鳞芽 10 d后长成小鳞茎 .The GUS gene was transformed into Narcissus tazetta mediated by Agrobacter ium tumefaciens . Bulbs of narcissus co cultivated 3 days after being transf ormed were detected by histochemical method, and GUS gene expressed perfectly. T here were large masses of blue patches on 90% of transformed materials. When sc reen cultured 20 days, about 1% tissues of the detected materials had long ter m expression of GUS gene. It indicated that GUS gene had been expressed steadil y. The frequency of transformation increased twice when narcissus pre cultured 10 days and agrobacterium was activated for 2～3 hours by 60 μmol/L AS before b eing transformed. Many bulbils outgrew from 60% of transformed materials which cultu red 20 days in MS+BA 10 +NAA 0.2 +Cef 300 +Hyg 30 medium, 5.7 bulbils on each tissue in average, and 14 at most.福建省自然科学基金 (C970 0 1);; 教育部访问学者基金资助项

Influence of Crystallinity on the Kinetics of Li Ion Insertation and Deinsertation in Spinel LiMn_(2)O_(4)

应用溶胶-凝胶法制备两种结晶度尖晶石锂锰氧化物.X射线衍射(XRD)、电感耦合等离子体原子发射光谱(ICP)、扫描电镜(SEM)、恒电流充放电、循环伏安(CV)和交流阻抗谱(EIS)等方法测试表明:以较高温度焙烧制得的L iMn2O4样品结晶度较高,但结晶度较低的样品却具有较高的放电容量和较好的循环稳定性,这主要是结晶度较低的样品具有较快的电荷交换速率和锂离子扩散速率.Two spinel lithium manganese oxides of different crystallinity were prepared by sol-gel process and were studied by using inducfively coupled plasma,X-ray diffraction,scaning electron micrographs,constant charging and discharging,cyclic voltammetry and electrochemical impedance spectrometry,the results show that the sample treated under 700 ℃ has higher crystallinity than the sample treated under 500 ℃,however,the sample with lower crystallinity has higher discharge capacity and better cyclic performance that due to quicker charge exchange speed and quicker diffusion speed of Li-ion.作者联系地址：华南师范大学化学与环境学院,华南师范大学化学与环境学院,华南师范大学化学与环境学院 广东广州510006,广东广州510006,广东广州510006Author's Address: School of Chemistry and Environment,South China Normal University,Guangzhou 510006,Guangdong,Chin

不同干预方式对提升初中生心理健康水平效果分析

随着社会的发展与竞争的加剧,我国青少年心理健康问题日益突出[1]。为提高初中生的综合素质,保障其健康成长,为社会未来经济建设和民族素质发展打下良好的人才基础。本研究拟通过感恩日记、心理健康辅导、综合心理辅导3种不同干预方式,对初中生心理健康水平进行测试,以了解南昌市初中生的心理健康现状,并建立有效的心理干预模式,提高初中生的心理健康水平。1对象与方法 1.1对象于2012年9月随机整群抽取南昌市第十二中学8个班级共496名初中生为调查对象。</p