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国家自然科学基金(10978006)

作品数:6 被引量:18H指数:3
相关作者:汪敏郝龙飞李志玄高冠男董亮更多>>
相关机构:中国科学院国家天文台中国科学院研究生院中国科学院更多>>
发文基金:国家自然科学基金国家重点基础研究发展计划更多>>
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组成干涉阵列的阵元数目问题研究
2012年
使用模拟干涉成像实验对组成干涉阵列的阵元数目进行讨论,假设分别使用从20个到100个天线组成干涉阵列,使用基因遗传优化的方法得出随天线数目的增加在旁瓣水平、能量覆盖率和平均方差等3种评价标准下的性能变化曲线,通过拟合得出天线数目与各种评价效果的函数对应关系,又进一步讨论了使用效果截断、增加阵元效率等方法为设计干涉阵列的阵元数目提出合理方案,为太阳低频射电阵列阵元数目的确定提供参考。
张远修汪敏
关键词:遗传算法优化
基于DBBC+Mark 5B记录系统的脉冲星观测被引量:5
2011年
2009年11月,云南天文台射电天文研究团组采用40 m射电望远镜以及基于DBBC(Digital Base Band Conveter)和Mark 5B的VLBI记录系统对PSR J0835-4510和PSRJ0332+5434进行了观测。观测选用S波段右旋圆极化信号,起始频率为2 206.99 MHz,总带宽为32 MHz。对数据进行相干消色散和平均后,得到PSR J0332+5434的单脉冲图像和两颗脉冲星的平均脉冲轮廓。由平均轮廓的展宽随时间的变化关系,对脉冲星的视周期作了一定修正后,得到信噪比更高的平均轮廓图。最后对轮廓的信噪比随时间的变化作了初步分析,由此可了解整个系统在观测时的稳定性。
李志玄汪敏郝龙飞罗近涛
Possible radio precursors/signatures of the CMEs onset:radio type Ⅲ bursts and fine structures in the centimeter-metric wavelength region被引量:2
2011年
Seventy-one occurrences of coronal mass ejections (CMEs) associated with radio bursts, seemingly associated with type III bursts/fine structures (FSs), in the centimeter-metric frequency range during 2003-2005, were obtained with the spectrometers at the National Astronomical Observatories, Chinese Academy of Sciences (NAOC) and the Culgoora radio spectrometer and are presented. The statistical results of 68 out of 71 events associated with the radio type III bursts or FSs during the initiation or early stages of the CMEs indicate that most CMEs contain the emissions of radio type III bursts/FSs near the time of the CME's onset, in spite of their fast or slow speeds. Therefore, we propose that type III bursts and FSs are possible precursors of the onset of CMEs. We stress that the radio type III bursts/FSs in the centimetermetric wavelength region and the CME transients possibly occurred in conjunction with the origin of the coronal precursor structures. Thus, the statistical results support the suggestions that type III bursts/FSs are indicators of extra energy input into the corona at the CMEs' onset, and that the type III bursts/FSs are produced primarily due to a coronal instability which eventually triggers the CME process. This may signify that the centimeter-metric radio bursts corresponding to or near the CME's onset are caused by the disturbed corona (possibly including minor magnetic reconnections).
MinWangGuan-NanGa01Rui-XiangXieCheng-MingTan
米波太阳射电频谱仪的科学目标和技术方案被引量:5
2011年
介绍了70~700 MHz低频太阳射电频谱仪的科学目标和技术方案,给出了11 m网状抛物面天线、接收系统、数字频谱终端的技术指标。并对系统的整机噪声系数、灵敏度、最小可测流量密度、LNA输入端的噪声功率进行了估计。系统频谱分辨率优于0.2MHz,时间分辨率最高可达2 ms。
施硕彪董亮高冠男汪敏夏志国
关键词:接收机噪声系数灵敏度
日冕物质抛射及其伴生的射电辐射观测特征被引量:1
2011年
统计分析了太阳活动周下降段(2003~2005年)发生的76个共生CME的射电爆发事件。射电爆发资料来自国家天文台和Culgoora的微波和米波频谱仪。在76个事件中有50个快速CME和26个慢速CME。从中发现,快速CME和慢速CME的产率分别随着太阳活动周的降低而下降和上升,这可能说明CME的产率与太阳活动周中日冕磁结构的位形和位置变化有关。同时也发现,射电爆发的类型和寿命有一个变化规律,即随着频率的降低射电爆发的寿命变长,此特征支持了伴生CME的II型爆发统一模型的思想。另外还发现在厘米—分米波范围,CME开始前后,容易发生射电III型爆发或快速精细结构。这说明射电辐射的精细结构可能是CME的前兆现象或CME早期发展阶段由于磁重联引发的低日冕小尺度磁扰动的结果。
谢瑞祥汪敏颜毅华谭程明
关键词:太阳CME射电爆发
VLBI observations with the Kunming 40-meter radio telescope被引量:5
2010年
The Kunming 40-meter radio telescope is situated in the yard of the Yunnan Astronomical Observatory (Longitude: 102.8° East, Latitude: 25.0° North) and saw its first light in 2006 May. The Kunming station successfully joined the VLBI tracking of China's first lunar probe "Chang'E-1" together with the other Chinese telescopes: the Beijing Miyun 50-meter radio telescope, Urumqi Nanshan 25-meter radio telescope, and Shanghai Sheshan 25-meter radio telescope, and received the downlinked scientific data together with the Miyun station from October of 2007 to March of 2009. We give an introduction to the new Chinese VLBI facility and investigate its potential applications. Due to its location, the Kunming station can significantly improve the u - v coverage of the European VLBI Network (EVN), in particular, in long baseline observations. We also report the results of the first EVN fringe-test experiment of N09SX1 with the Kunming station. The first fringes in the European telescopes were successfully detected at 2.3 GHz with the ftp-transferred data on 2009 June 17. From scheduling the observations to performing the post correlations, the Kunming station shows its good compatibility to work with the EVN. The imaging result of the extended source 1156+295 further demonstrates that the Kunming station greatly enhances the EVN performance.
Long-Fei HaoMin WangJun Yang
关键词:INTERFEROMETERSVLBI
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