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221.
Sneha Yadav Rupesh M. Das R.S. Dabas A.K. Gwal 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The digital ionosonde located in Bhopal (23.2°N, 77.2°E), India has been used to investigate the responses of the Es layer in the equatorial ionization anomaly (EIA) crest to the total solar eclipse (TSE) of July 22, 2009. Results show the presence of intense Es layer during and after the eclipse period. The gravity waves induced by the solar eclipse propagated upward in the Es layer and produced the periodic disturbance. The results of the wavelet analysis display the presence of dominant oscillation of about 24–32, 16–20 and 8 min. The appearance of intense sporadic-E concomitantly with the signatures of gravity wave suggests that the wind shear introduced by the solar eclipse induced gravity wave might be the plausible mechanism behind the intensification of Es-layer ionization. 相似文献
222.
F. El-Lemdani Mazouz J.L. Rauch P.M.E. Décréau J.G. Trotignon X. Vallières F. Darrouzet P. Canu X. Suraud 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Intense (n + 1/2) fce emissions are a common phenomenon observed in the terrestrial inner magnetosphere. One of their interests is their possible effect in the pitch angle scattering of plasmasheet keV-electron, leading to diffuse auroras. In this paper, we present CLUSTER’s point of view about this topic, in the equatorial region of the plasmasphere, via a statistical study using 3 years of data. Spectral characteristics of these waves, which represent an important clue concerning their generation mechanism, are obtained using WHISPER data near perigee. Details on the wave spectral signature are shown in an event study, in particular their splitting in fine frequency bands. The orbit configuration of the four spacecraft offers a complete sampling on all MLT sectors. A higher occurrence rate of the emissions in the dawn sector and their confinement to the geomagnetic equator, pointed out in previous studies, are confirmed and described with additional details. The proximity of emission sites, both to the plasmapause layer and to the geomagnetic equator surface, seems to be of great importance in the behaviour of the (n + 1/2) fce wave characteristics. Our study indicates for the first time, that both the intensity of (n + 1/2) fce emissions, and the number of harmonic bands they cover, are increasing as the observation point is located further away outside from the plasmapause layer. Moreover, a study of the wave intensity in the first harmonic band (near 3/2 fce) shows higher amplitude for these emissions than previous published values, these emissions can play a role in the scattering of hot electrons. Finally, geomagnetic activity influence, studied via time series of the Dst index preceding observations, indicates that (n + 1/2) fce emission events are observed at CLUSTER position under moderate geomagnetic activity conditions, no specific Dst time variation being required. 相似文献
223.
T.H. Oswald W. Macher H.O. Rucker G. Fischer U. Taubenschuss J.L. Bougeret A. Lecacheux M.L. Kaiser K. Goetz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
On October 25th, 2006, NASA’s two STEREO spacecraft were launched which are designed to increase our knowledge of the physics of the solar system. On board they carry a sophisticated radio experiment, called S/WAVES. The key technology, used by S/WAVES is the direction finding capability in addition to the use of two spacecraft which makes it possible to triangulate radio sources. Direction finding requires the reception properties of the antennas to be known very accurately. We applied several different methods to calibrate the S/WAVES antennas. In this paper the methods are described and compared and the results are presented and discussed with respect to advantages and disadvantages of the different methods. 相似文献
224.
纤维素甘油醚硝酸酯NGEC是一种改性硝化棉,以NGEC为粘合剂代替NC,采用传统的无溶剂法制备了NGEC基改性双基推进剂。研究了以NGEC为粘合剂的改性双基推进剂的力学、燃烧和弹道性能及燃烧波结构。结果表明,NGEC具有较好的热塑性,NGEC基改性双基推进剂加工性能优良,其低温-40℃延伸率可达相同配方NC基改性双基推进剂的1.5倍以上,其推进剂弹道性能稳定,燃烧性能和燃烧波结构与NC基推进剂相似。因此,NGEC作为含能粘合剂代替NC,可用于改善改性双基推进剂性能的研究。 相似文献
225.
226.
Suess S. T. Phillips J. L. McComas D. J. Goldstein B. E. Neugebauer M. Nerney S. 《Space Science Reviews》1998,83(1-2):75-86
The solar wind in the inner heliosphere, inside ~ 5 AU, has been almost fully characterized by the addition of the high heliographic latitude Ulysses mission to the many low latitude inner heliosphere missions that preceded it. The two major omissions are the high latitude solar wind at solar maximum, which will be measured during the second Ulysses polar passages, and the solar wind near the Sun, which could be analyzed by a Solar Probe mission. Here, existing knowledge of the global solar wind in the inner heliosphere is summarized in the context of the new results from Ulysses. 相似文献
227.
本文提出对风扇机匣应进行行波振动分析, 作出频率响应曲线, 进行限幅设计。在分析过程中, 根据结构特点给出了模型的简化方法, 采取周期对称模型, 并根据周期对称的理论结合激振力的特点给出了旋转脉动激励在周期对称模块中的施加方法。 相似文献
228.
HIGHORDERACCURACYSCHEMEFOR2-DTRANSONICFLOWS¥LiHaidong;LiuQiusheng;ShenMengyu(DepartmentofEngineeringMechanics,TsinghuaUnivers... 相似文献
229.
230.
NND格式的推广及在粘流计算中的应用 总被引:7,自引:3,他引:7
本文把NND格式推广到了特征变量,守恒变量和原始变量形式。通过引入通量差分分裂方法,由守恒变量形式的NND格式得到了Roe的近拟Riemann解法,并讨论了限制器的作用。在隐式NND格式中引入了一种分解算法,提高了计算效率。本文的数值计算表明,NND格式对复杂波系干扰,边界层分离与再附等流动现象均有较高的分辨率。 相似文献