The relationship between ionospheric total electron content (TEC) over East Asia and the tropospheric circulation around the Qinghai-Tibet Plateau obtained with a partial correlation method

This paper reports a study on the relationship between ionospheric total electron content (TEC) over East Asia and the tropospheric circulation around the Qinghai-Tibet Plateau. Ionospheric TEC over East Asia are obtained from 25 observatories during 1996–2004. By applying a partial correlation method which can eliminate the influences of solar and geomagnetic activities, we find no significant correlation between TEC and the Asian zonal circulation index (Iz), but find a positive correlation between the day-to-day variability of TEC and Iz. We suggest that the positive correlation is closely related with the topography of the Qinghai-Tibet Plateau. The dynamical effect on airflow of the plateau can generate vortexes, and the vortexes may continuously excite internal gravity waves (IGWs) which transmit up to the ionosphere and cause regional wave disturbances. This study gives evidence for the dynamical mechanism of ionosphere–troposphere coupling and shows the importance of the Qinghai-Tibet Plateau in the ionosphere–troposphere coupling over East Asia.     

单自由度扑翼模型脱落涡及其升力机制的实验研究

采用色流实验与particle image velocimetry(PIV)测量相结合的方法,对单自由度扑翼模型所产生的脱落涡进行实验研究,得到以下结论:①在扑翼上扑或下扑的过程中,前后缘处产生连续的牛角形涡环,且脱落涡均存在展向运动.②翼翅表面脱落涡的交替产生,使得翼翅上下表面交替产生不对称分布的压力差.③研究对象产生升力的条件是攻角与来流速度均不为零.④扑翼上扑和下扑过程中,脱落涡环量最大值均出现在单行程的3/5处.⑤脱落涡环量与扑动速度成正比.⑥相比上扑过程,下扑过程中翼翅对流场做功更多,在一个扑动周期内,这多余的能量转换为扑翼升力.     

基于全自由尾涡模型的最佳环量分布风力机叶片气动优化方法

通过优化环量分布,开发了一种快速的风力机叶片气动优化设计方法.方法中引入了全自由尾涡模型,通过并行处理技术和快速多极子方法加速计算.采用傅里叶级数参数化叶片附着涡环量分布,大幅减少了优化变量数目.以风能利用系数为目标函数,以给定轴向力系数为约束条件,获得环量分布后反求得到叶片最优几何参数.最后通过优化美国可再生能源实验室（NREL）实验风轮进行方法验证,结果表明:在约束条件下,当尖速比分别为3.79和4.74时,优化使风轮的风能利用系数分别提升了32%和8%.在无约束条件下,针对不同叶片数和尖速比,分别对原NREL风轮进行全局优化,得到了风能利用系数均超过0.48以上的最优设计.      

基于CFD研究等离子体环量控制流场特性

为了研究等离子体气动激励射流在翼型钝尾缘产生Coanda效应时对流场特性的影响,基于雷诺平均N-S方程中添加体积力源项的唯象学仿真方法,建立并优化了等离子体环量控制的数值计算模型,研究了基于分离点的不同激励器位置对流场的影响规律。结果表明,优化激励器位置后环量控制的效费比ΔCL／Cμ最高可以达到113．49。分析发现,当等离子体激励产生的激励射流刚好可以将分离点推移至压力面时,机翼有效弯度增加最为明显,激励效果最好。     

Recent advances in observing mesoscale ocean dynamics with satellite altimetry

The paper provides a review of recent results on mesoscale ocean dynamics derived from satellite altimetry. Since 1992, we have had an unprecedented 18 year high-resolution monitoring of the ocean mesoscale field. Altimetry is often used in mesoscale studies in synergy with other remote sensing techniques and in situ data. This global, high-resolution data set has allowed oceanographers to quantify the previously unknown seasonal and interannual variations in eddy kinetic energy and eddy heat and salt transports, and investigate their causes. Eddy tracking techniques have allowed us to monitor their propagation pathways, to bring to light the meridional divergence of cyclones and anticyclones, and to question the role of Rossby waves versus non-linear eddies in the mid to high latitude bands. Altimetry has also revealed the presence of zonal fronts and jets everywhere in the ocean, and brought to light how mesoscale eddies can impact back onto the atmospheric circulation. Finally, altimetry, in synergy with other observations and high-resolution numerical models, has helped reveal the complexity of the sub-mesoscale features, associated with stirring and mixing around the mesoscale eddies, of great importance for the vertical exchange of oceanic tracers. Altimetry has revealed the complexity of the mesoscale system… the scientific community is now working to understand the interplay between these mesoscale eddies, the ocean interior and its impact on the overlying atmosphere.     

圆柱绕流的环量控制

对用壁面射流控制圆柱绕流的问题进行了研究,并探讨了喷口位置、多喷口吹气等问题。结果表明,喷口位置对圆形翼型的气动特性影响很大;多喷口吹气既可以提高圆形翼型的最大升力系数又可以降低吹气的能量消耗。     

论公司外部利益循环

从"三挺政策"分析公司外部利益循环,提出公司外部利益循环将面临公司内部权力配置"协同化"的新趋势,对公司股东与外部相关者的利益以及公司的长远发展会产生一定影响。     

双翼尖涡Rayleigh—Ludwieg不稳定性实验研究

采用一种结构化矩形直机翼涡发生器产生一对大小不同、方向相反的翼尖涡,调节双涡涡量的大小比例Г1／Г2及其间距b,触发两涡Rayleigh—Ludwieg不稳定性。实验采用流动显示方法定性观察双涡相互作用过程,通过二维PIV（粒子成像测速）系统定量研究双涡相互作用特征,得到双翼尖涡中主涡及次涡的运动特性、环量-时间特性。对不同实验参数下残余环量比例进行分析,发现双涡涡量大小比例Г1／Г2在1．3～1．4、b为50ram时双涡相交削弱效果良好,能够实现翼尖涡强序削弱程度扶30％～40％。     

稳定射流环量控制的仿真研究

为改善飞行器的升阻特性,提高其机动性能,利用数值仿真技术对稳定射流在超临界翼型的作用效果进行研究。通过动量系数变化对环量控制作用效果影响规律的研究分析后发现:稳定射流环量控制与无射流情况对比,有较强的优越性,在小迎角或负迎角就可以产生较大的升力。通过对后缘半径和射流口高度的变化对环量控制作用效果影响规律的研究分析,得到圆形后缘超临界环量控制翼型的初步设计方法。计算结果可为进一步研究环量控制对飞行器的影响奠定理论基础。     

Automated determination of the orientation of dust devil tracks in mars orbiter images

The paper presents and evaluates three methods for automatically estimating the main orientation of Martian dust devil tracks in MOC and HiRISE images. Inferring such information about dust devils from their tracks is important to better understand the near surface wind. The methods considered were based on gradient direction, directional openings and morphological granulometry. The accuracy of the methods was asserted by comparing the results to a set of directions estimated visually and assumed to be the ground truth. The higher accuracy was reached using directional openings. Besides, the directions inferred by this method were compared to those predicted by the GCM and the results agreed.