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41.
H. J. Völk 《Space Science Reviews》2007,130(1-4):431-438
The dynamical and chemical effects of the Galactic Wind are discussed. This wind is primarily driven by the pressure gradient
of the Cosmic Rays. Assuming the latter to be accelerated in the Supernova Remnants of the disk which at the same time produce
the Hot Interstellar Medium, it is argued that the gas removed by the wind is enriched in the nucleosynthesis products of
Supernova explosions. Therefore the moderate mass loss through this wind should still be able to remove a substantial amount
of metals, opening the way for stars to produce more metals than observed in the disk, by e.g. assuming a Salpeter-type stellar
initial mass function beyond a few Solar masses. The wind also allows a global, physically appealing interpretation of Cosmic
Ray propagation and escape from the Galaxy. In addition the spiral structure of the disk induces periodic pressure waves in
the expanding wind that become a sawtooth shock wave train at large distances which can re-accelerate “knee” particles coming
from the disk sources. This new Galactic Cosmic Ray component can reach energies of a few×1018 eV and may contribute to the juncture between the particles of Galactic and extragalactic origin in the observed overall
Cosmic Ray spectrum. 相似文献
42.
介绍了卫星在热平衡试验后所发现的有效载荷的污染情况,通过对污染提取物的分析和试验设备的再次污染监测,找出了污染源,并对以后的防污染工作提供了借鉴. 相似文献
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44.
用溶胶-凝胶法在非晶玻璃上制备VO2薄膜,经过熔融、涂膜、烘干和热处理等工艺最后得到电阻相变2-3个量级的VO2薄膜。对烘干温度、熔融温度、膜厚和热处理温度对薄膜电阻开关特性的影响进行了研究。通过XRD(X-ray diffraction)和XPS(X-ray photoelectron spectroscopy)对薄膜的结构和价态进行分析,表明用溶胶-凝胶法制图VO2膜工艺简单,重复性好。 相似文献
45.
基于有限元法的隧道荷载模型位移反分析 总被引:1,自引:0,他引:1
李誉 《中国民航学院学报》2006,24(1):42-45
介绍了一种以荷载模型为求解对象的位移反分析法。它是以通用有限元软件为实验平台,利用隧道位移实测值建立荷载灵敏系数方程,根据最小二乘法原理反求隧道模型的荷载,再将正分析结果和实际值进行对比分析井重新调整隧道荷载模型,最终获得较为符合实际的隧道荷载模型。该方法的优点是既考虑了岩土松动荷载效应又能体现支护结构与周围岩土体的共同作用,且具有较好的操作性。 相似文献
46.
A.G. Lyne 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2716-2720
A recent multibeam pulsar survey of the outer Galactic plane at Parkes has discovered the first-known double-pulsar binary, a very compact double neutron star system in which both stars are observable as radio pulsars. In this review, we briefly describe the discovery and the studies which have been enabled by the unique properties of the system. These range from the most precise confirmation yet of the theory of general relativity, with the possibility of even more new tests and the measurement of second-order post-Newtonian effects, to studies of the magnetospheres and emission properties of the two pulsars. The discovery also results in a significant increase in the expected rate of occurrence of the mergers of double neutron star systems, and hence the rate of detection of such events by the new ground-based gravitational wave detectors. 相似文献
47.
The Bastille-day event in 2000 produced energetic 3B/X5.6 flare with a halo CME, which had great geo-effects consequently.
This event has been studied extensively and it is considered that it follows the two-ribbon flare model. The flare/CME event
was triggered by an erupting filament and TRACE observations showed formation of giant arcade structures during the flare
process. Hard X-ray (HXR) two ribbons revealed for the first time in this flare event (Masuda et al., 2001). The reconstruction of 3-D coronal magnetic fields revealed a magnetic flux rope structure, for the first time, from
extrapolation of observed photospheric vector magnetogram data and the flux rope structure was co-spatial with portion of
the filament and a UV bright lane (Yan et al., 2001a, 2001b). Here we review some recent work related to the flux rope structure and the HXR two ribbons by comparing their
locations and the flux temporal profiles during the flare process so as to understand the energy release and particle accelerations.
It is proposed that the rope instability may have triggered the flare event, and reconnection may occur during this process.
The drifting pulsation structure in the decimetric frequency range is considered to manifest the rope ejection, or the initial
phase of the coronal mass ejection. The HXR two ribbons were distributed along the flux rope and the rope foot points coincide
with HXR sources. The energy dissipation from IPS observations occurred within about 100 R
⋅ is consistent with the estimate for the flux rope system.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
48.
陈德贤 《郑州航空工业管理学院学报(管理科学版)》2005,23(3):83-86
文章推导出了企业职工养老金替代率的计算公式,对影响替代率的五个因素分别进行了灵敏性分析,给出了替代率的最佳可行区域. 相似文献
49.
50.