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V.V. Zharkova S.I. Zharkov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(6):881-892
The Solar Feature Catalogues for sunspots and active regions measured with SOHO/MDI instrument and Ca II K3 spectroheliograph of the Paris-Meudon Observatory are analyzed with the automated classification technique for sunspot groups and active region polarities. We report the first classification results for daily variations of tilt angles (normal and trigonometric ones) in sunspot groups (SG) and active (AR) regions in the cycle 23. The average normal tilts are presented for every year at the ascending and descending phases of the cycle 23 which are similar to those deduced by other authors for the cycles 19–22. The normal tilts of both the sunspot groups and active regions are shown to increase in the ascending phase and a decrease in the descending phase. Similar to SG and AR areas, the trigonometric tilts are shown to have the noticeable North–South asymmetry with the Southern hemisphere dominant in the selected ascending and descending periods. The normal tilt variations with latitude follow Joy’s law revealing a periodicity along the meridian of about 10° and reaching the maximum of 14° at the latitude of about 32° corresponding to the top of the ‘royal zone’ where the sunspots appear. The variations of polarity separation with a latitude are in an anti-phase with those of the tilts reaching a maximum at the latitude of 35° and showing a small positive separation for the groups/active regions in a vicinity of the average tilts ±40°. The ratio R of the polarity separation to the trigonometric tilt fits the linear function of a latitude φ as R = −0.0213φ − 0.1245 confirming positive separation for the polarities of active regions with the average tilts, or the dominance of activity in the Southern hemisphere activity, for the selected period of observations. 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014,54(7):1434-1438
Broad absorption line (BAL) variability potentially represents a powerful tool to investigate the physical nature and the structure of gas outflows in active galactic nuclei. Most existing BAL variability studies rely on observations taken at a few epochs for samples of tens of BAL QSOs. In this study we present the first “monitoring” of a single object, APM 08279+5255, which has been observed more than 20 times since 2003. All available spectra from the literature have also been analysed, including two high resolution spectra, extending the time interval from 1998 to 2012. A relative stability of the shape of the absorption profile is found. At the same time significant variations of the equivalent width are observed. A correlation of the BAL equivalent width with the QSO luminosity is found for the first time. These results suggest that changes in the ionisation state of the gas are causing opacity changes. 相似文献
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F.X. Esnault N. Rossetto D. Holleville J. Delporte N. Dimarcq 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
HORACE (HOrloge à Refroidissement d’Atomes en Cellule = clock based on atoms cooled from vapour cell) is a compact cold caesium atom clock developed in SYRTE at Paris Observatory. This clock can operate both on ground and in microgravity environment. Design of HORACE is based on isotropic light cooling, allowing performing the whole clock sequence (cooling, atomic preparation, Ramsey interrogation and detection) at the same place. Compared to more conventional cold atom clocks such as atomic fountains, the use of isotropic light cooling simplifies both the optical part of the setup and the detection sequence, and leads to a drastic size reduction of the physics package. Very good short-term performances have been demonstrated at SYRTE since relative frequency instability of 2.2 × 10−13 τ−1/2 has been obtained. Optimization of the long term stability is still under progress and current results show relative frequency instability around 3 × 10−15 in 104 s of integration. With these performances, HORACE appears as a good candidate both for Galileo’s ground segment clock and for onboard Galileo clock. 相似文献
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胡经纬 《沈阳航空工业学院学报》2001,18(2):75-78
本文对北京一高层建筑采暖空调系统进行了技术改造方案论证,通过对技术先进性及适用性、改造繁简程度、设备寿命以及运行等诸方面的综合技术分析,确定采用新型螺杆冷水机组+燃气热水锅炉的方案。新的供暖空调系统安全高效运行并提供了高品质人工环境。 相似文献
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放宽静稳定性在空空导弹总体设计中的应用 总被引:3,自引:0,他引:3
将主动控制技术引入空空导弹总体设计中,研究了空空导弹放宽静稳定性设计问题,讨论了放宽静稳定性设计对导弹性能的改善,最后给出了静不稳定弹体的系统稳定性判定条件,并着重讨论了静不稳定弹体的人工稳定问题,研究结果对于新一代先进空空导弹的总体设计工作有一定的参考价值。 相似文献
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介绍了几种液体火箭发动机喷注喷研制中出现的技术问题及其解决途径。同时,对双组元离心式喷嘴流量偏差作了分析,探讨了控制流量偏差的方法。提出的一种身部内冷却装置,采用斜齿缝隙钎焊整体式结构,在中等推力液体火箭发动机中进行试验得出初步结论。 相似文献
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