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961.
Roberto Bruno Bruno Bavassano Raffaella D’amicis Vincenzo Carbone Luca Sorriso-Valvo Ermanno Pietropaolo 《Space Science Reviews》2006,122(1-4):321-328
The observations at different solar distances and latitudes, collected in the past three decades, and the results obtained
from more and more sophisticated numerical simulations allowed us to reach a good understanding on many aspects of the complex
phenomenon of solar wind turbulence. Moreover, new interesting insights in the theory of turbulence have been obtained, in
the past decade, from the point of view that considers a turbulent flow as a complex system, where chaotic behavior and well-established
scaling laws coexist. This review aims to provide a quick overview on the state of art in this research field with particular
focus on local generation mechanisms. 相似文献
962.
对具有橡胶——惯性结构的火箭发动机机架简化模型中动态载荷传播特性进行了研究。机架内动态载荷在依次通过橡胶-惯性结构粘贴位置时,携带的部分动能传递到橡胶材料内,导致机架内应力幅值显著低于能量交换前的应力。通过分析橡胶材料内外表面的速度,发现速度差引起了橡胶阻尼材料沿轴向发生剪切加载和卸载过程,并导致机架传递到橡胶材料的动态能量发生剪切变形的过程中被耗散吸收;此外,机架内动态载荷大小与机架内质点速度的变化量有关,机架内质点动能减小及运动速度降低是引起机架动态载荷幅值降低的根本原因。 相似文献
963.
Jeongwoo Lee 《Space Science Reviews》2007,133(1-4):73-102
Solar active region coronae are known for strong magnetic fields permeating tenuous plasma, which makes them an ideal astronomical
laboratory for magnetohydrodynamics research. It is, however, relatively less known that this physical condition also permits
a very efficient radiation mechanism, gyro-resonant emission, produced by hot electrons gyrating in the coronal magnetic field.
As a resonant mechanism, gyro-emission produces high enough opacity to fully reveal the coronal temperature, and is concentrated
at a few harmonics of the local gyrofrequency to serve as an excellent indicator of the magnetic field. In addition, the polarization
of the ubiquitous free–free emission and a phenomenon of depolarization due to mode coupling extend the magnetic field diagnostic
to a wide range of coronal heights. The ability to measure the coronal temperature and magnetic field without the complications
that arise in other radiative inversion problems is a particular advantage for the active region radio emissions available
only at these wavelengths. This article reviews the efforts to understand these radiative processes, and use them as diagnostic
tools to address a number of critical issues involved with active regions. 相似文献
964.
R. A. Mewaldt C. M. S. Cohen G. M. Mason A. C. Cummings M. I. Desai R. A. Leske J. Raines E. C. Stone M. E. Wiedenbeck T. T. von Rosenvinge T. H. Zurbuchen 《Space Science Reviews》2007,130(1-4):207-219
Although the average composition of solar energetic particles (SEPs) and the bulk solar wind are similar in a number of ways,
there are key differences which imply that solar wind is not the principal seed population for SEPs accelerated by coronal
mass ejection (CME) driven shocks. This paper reviews these composition differences and considers the composition of other
possible seed populations, including coronal material, impulsive flare material, and interplanetary CME material. 相似文献
965.
Delaunay非结构网格生成之布点技术 总被引:4,自引:0,他引:4
Delaunay 非结构网格生成技术是 C F D 领域广为应用的有效技术之一。如何布置流场中的计算点是 Delaunay 三角剖分的一个关键问题。本文以二维非结构网格生成为例, 介绍三种布点策略, 即重心布点、外接圆心布点和 Voronoi 边布点, 算例表明三种方法均可生成满意的非结构网格, 其中 Voronoi 边布点方法生成的网格质量更好一些。三种方法均可方便地推广到三维问题。 相似文献
966.
Magneto-gravity Waves Trapped in the Lower Solar Corona 总被引:1,自引:0,他引:1
Yu-Qing Lou 《Space Science Reviews》1999,87(1-2):261-264
The possibility of trapped magneto-gravity waves in the lower solar corona with an open magnetic field is discussed. Intensity
variations and/or Doppler shifts of relevant UV, EUV and x-ray spectral lines in the chromosphere, transition region and lower
corona may reveal the existence of such low-frequency modes (with periods longer than ∼ 1.5 hour). The spectrum may be either
discrete or continuous depending on the reflection property of the narrow transition region. These modes can be utilized to
probe the dynamics of the upper chromosphere, transition region and lower corona; they may also play an important role in
coronal heating.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
967.
M. Verigin D. Vignes D. Crider J. Slavin M. Acua G. Kotova A. Remizov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,33(12):2222-2227
The origin of the anisotropy in the shape of the Martian obstacle and bow shock is analyzed using Mars Global Surveyor observations. The influence of MHD or ion pick-up effects on Martian obstacle position was to be small found, however, localized Martian crustal magnetization increases the thickness of the downstream planetary magnetotail by 500–1000 km in agreement with earlier Phobos 2 observations. A new analytical model is presented for Martian obstacle shape variation for different solar wind ram pressure. Elongation of the Martian BS cross-section in the direction perpendicular to IMF was confirmed while the shift of this cross section in the +Y direction of Martian interplanetary medium reference frame was discovered. The shift of BS cross section in the direction of interplanetary electric field was not revealed thus not conforming the idea that mass-loading play some role in BS control. 相似文献
968.
969.
J. L. Burch R. Goldstein T. E. Cravens W. C. Gibson R. N. Lundin C. J. Pollock J. D. Winningham D. T. Young 《Space Science Reviews》2007,128(1-4):697-712
The ion and electron sensor (IES) is part of the Rosetta Plasma Consortium (RPC). The IES consists of two electrostatic plasma
analyzers, one each for ions and electrons, which share a common entrance aperture. Each analyzer covers an energy/charge
range from 1 eV/e to 22 keV/e with a resolution of 4%. Electrostatic deflection is used at the entrance aperture to achieve
a field of view of 90°× 360° (2.8π sr). Angular resolution is 5°× 22.5° for electrons and 5°× 45° for ions with the sector
containing the solar wind being further segmented to 5°× 5°. The three-dimensional plasma distributions obtained by IES will
be used to investigate the interaction of the solar wind with asteroids Steins and Lutetia and the coma and nucleus of comet
67P/Churyumov–Gerasimenko (CG). In addition, photoelectron spectra obtained at these bodies will help determine their composition. 相似文献
970.
机电产品安全风险评价模型研究 总被引:2,自引:0,他引:2
目前,我国的机电产品在其全寿命周期中基本上不做安全风险评价,一个重要的原因是缺乏有效的风险评价模型。为此,本文提出了一种适合于我国机电产品在设计阶段进行风险评价的通用模型。 相似文献