Vertical wavenumber spectra of atmospheric ozone measured from ozonesonde observations

Vertical profiles of ozone have been measured at balloon altitudes. Our purpose is to examine the character of vertical wavenumber spectra of ozone fluctuations, to assess the possible roles of gravity wave field in ozone fluctuations, and to determine dominant vertical wavelengths of ozone spectra. Vertical wavenumber spectra of 12 ozone fluctuations obtained during June–August 2003 are presented. Results indicate that mean spectral slopes in the wavenumber range from 4.69 × 10⁻⁴ to 2.50 × 10⁻³ cyc/m are about −2.91 in the troposphere and −2.87 in the lower stratosphere, which is close to the slope of −3 predicted by current gravity wave saturation models. The consistency of the observed spectral slopes with the value of −3 predicted by current gravity wave saturation models suggests that the observed ozone fluctuations are due primarily to atmospheric gravity waves. At m = 1/(1000 m) the mean spectral amplitude is over 30 times larger in the lower stratosphere than in the troposphere. Mean vertical wavenumber spectra in area-preserving form reveal dominant vertical wavelengths of ∼2.6 km in the troposphere and ∼2.7 km in the lower stratosphere, which is consistent with the values varying between 1.5 and 3.0 km estimated from the velocity field and temperature field at these heights.     

A study of a long duration B9 flare-CME event and associated shock

We present and discuss here the observations of a small long duration GOES B-class flare associated with a quiescent filament eruption, a global EUV wave and a CME on 2011 May 11. The event was well observed by the Solar Dynamics Observatory (SDO), GONG H$\alpha$, STEREO and Culgoora spectrograph. As the filament erupted, ahead of the filament we observed the propagation of EIT wave fronts, as well as two flare ribbons on both sides of the polarity inversion line (PIL) on the solar surface. The observations show the co-existence of two types of EUV waves, i.e., a fast and a slow one. A type II radio burst with up to the third harmonic component was also associated with this event. The evolution of photospheric magnetic field showed flux emergence and cancellation at the filament site before its eruption.     

大气中激光等离子体通道的传播特性分析

对大气中激光等离子体通道的传播终端特性进行了研究。建立了大气中激光等离子体通道的近似电磁模型,基于圆柱坐标系中纵向分量所满足的波动方程,给出了纵向场与横向场的关系,由边界条件导出了大气中激光等离子体通道的特征方程。特征方程的数值解获得了相应色散曲线。     

非均匀磁化等离子体层的电磁特性分析

基于分层传播原理提出了一种计算电磁波在非均匀磁化等离子体层中反射率和吸收率的模型,并数值分析了等离子体密度与碰撞频率,以及背景磁场强度对电磁波的反射和吸收特性的影响.研究表明:该法所得结果与文献的传播矩阵(SMM)法一致.数值分析发现:低密度高碰撞频率等离子体可减少等离子体层对入射波的功率反射;高密度高碰撞频率等离子体可改善其对入射波的功率反射宽频带吸收特性;背景磁场强度可明显改变等离子共振吸收频段.     

行波液体静压轴承浮力及其稳定方法的实验研究

提出了一种基于蠕动传输作用的新型行波液体静压轴承。首先基于行波液体静压轴承原理,建立了轴承原理验证装置。然后基于差动螺纹机构建立了轴承面倾斜调整机构,实现轴承的完全上浮。利用所开发的轴承验证装置,实验研究了行波液体静压轴承在上浮方向上有导轨时的轴承承载能力,证明了行波液体静压轴承及其稳定方法的可行性,并给出了驱动参数,例如:驱动电压和驱动频率,以及轴承间隙高度对轴承浮力稳态值的影响规律。     

真实火箭燃气流场的测量与数值仿真

对用激光－莫尔偏折法测出的真实火箭燃气射流流场进行了数值仿真,在计算中采用了二阶精度的ＭＵＳＣＬ格式,将三维问题转化为二维问题,结果表明,理论计算与实验测量结果符合较好。     

数值模拟中的边界处理方法研究

为适应于模拟超声速流场中的一些特殊物理现象,研究了不同物理现象对边界处理的要求。针对激波、旋涡和声波等流场中典型的流动现象,采用常用的外推、特征和缓冲三类边界处理方法分别进行数值模拟。计算结果表明超声速流场边界采用外推技术,只适于计算带有激波的边界。特征方法还能适于旋涡运动的计算。声波的计算只能采用缓冲层技术。     

NEW APPROACH TO OBTAIN SPACE-TIME CONSERVATION SCHEMES

Inordertoovercometheseverallimitationsofthetraditionalmetheds,anewnumericalmethodofspace-timeconservationelementandsolutionelement(CE/SE)forsolvingconser-vationlawswasdevelopedbyChang['j.Thismethoddifferssubstantiallyinbothconceptandmethedologyfromthewell-establishedmethodslsuchasfinitedifference,finiteelement,etc.,andithasmanynontraditionalfeatures.First,spaceandtimeareunifiedandtreatedonthesamefooting,andbytheintroductionofconservationelementandsolutionelement,bothlocalandglobalfluxconserv…     

交流变频调速系统的SPWM波形生成方法的谐波分析

本文简述了交流变频调速系统常用的四种ＳＰＷＭ波形生成的方法，并研究了各种方法的ＳＰＷＭ开关点计算公式及其推导，利用这些公式计算了一系列开关点数据，同时提出了一种以开关点数据分析ＳＰＷＭ波形各次谐波的方法，通过谐波分析证实自然采样法优于其他方法。     

计及电离层倾斜的P—D变换及其短波通信MUF的预报方法

本文提出了计及电离层倾斜的高频返回散射电离图的最小时延换算为大圆距离的计算方法，并讨论利用返回散射电离图进行最高可用频率预报。在Ｄ＞１０００ｋｍ条件下，Ｐ－Ｄ变换的最大误差在３．５％以内，实时预报结果与ＣＣＩＲ提供的频率预报的月平均值相差±１．５ＭＨＺ．