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101.
LIU Guoping OUYANG Ziyuan LI Chunlai LIU Jianfeng National Astronomical Observatories Chinese Academy of Sciences Beijing Peking University of Aeronautics Astronautics Beijing 《《地质学报》英文版》2004,78(5):1104-1108
The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have their own local networks and interconnect with each other through access to the core data network. This paper describes the clock drift in the computer and other networked devices building up the infrastructure of the above local networks. The network time variance of the stochastic model is also estimated. The poor precision of network synchronization will bring about potential hazards to the network operation and application running in the networks, which is clarified in the present paper. At the end of the paper, a cost-effective and feasible solution is proposed based on the Global Position System (GPS) and the Network Time Protocol (NTP). 相似文献
102.
YIN Zhi-qiang ) HAN Yan-ben ) XU Dao-yi ) YAO Yi-Min ) HAN Yong-gang ) ) National Astronomical Observatories Chinese Academy of Sciences Beijing ) Institute of Geology China Earthquake Administration Beijing ) Geological Scientific Research Institute of Shengli Oilfield Company SINOPEC Dongying 《地层学杂志》2007,(Z2)
地球轨道要素的变化已作为确定地质年表的一种重要依据。应用地球轨道参数变化理论计算值来进行小波分析,结果清楚地展示出偏心率值约100ka、405ka、1Myr和2.3Myr等周期成份的随时间变化特征,100ka和405ka周期的振幅强度的变化成反相位关系,2.3Myr周期对100ka和405ka周期成份有调制作用。0—51Ma范围内变化较为稳定的地球轨道偏心率值的变化分析可以为地质年龄的划分和对比提供一定的参考。 相似文献
103.
Tao An Xiao-Yu Hong Wen-Xia Feng Jun-Hui Zhao Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai National Astronomical Observatories Chinese Academy of Sciences Beijing Harvard-Smithsonian Center for Astrophysics Garden Street MS Cambridge MA 《中国天文和天体物理学报》2004,4(6):527-532
We observed 1938-155, a broad line radio galaxy (BLRG), with the Very Large Array (VLA) at 90cm with an angular resolution of 6.8" × 4.0". The source consists of two components separated by 4 arcsec (- 20kpc, for H0 = 65km s-1 Mpc-1, q0 = 0.5) along the SE-NW direction. Both components show steep-spectra with a similar spectral index α - 0.83 ± 0.07 (Sv ∝ v-α). The bright double components are surrounded by a low-brightness cocoon. The radio properties of the two bright components are consistent with the hot spots produced by twin jets. An upper limit of - 0.0008 for the core dominance parameter (R) is inferred, suggesting there is no prominent radio core in the source. Assuming a modest viewing angle 30f77, a jet velocity is estimated - 0.07 c, based on the jet to counter-jet brightness ratio (J). The lower limit in jet speed inferred is consistent with no Doppler beaming effect on the jet. The radio galaxy 1938-155 could be an exceptional BLRG with no prominent radio core or jet. 相似文献
104.
Wang-Ping Zhou Yi Zheng Wei Guo Li Yu Chang-Song Yang School of Information & Control Engineering Nanjing University of Information Science & Technology Nanjing China Nanjing Institute of Astronomical Optics & Technology National Astronomical Observatories Chinese Academy of Sciences Nanjing 《中国天文和天体物理学报》2010,10(1)
Heavy disturbances caused mainly by wind and friction in the mount drive system greatly impair the pointing accuracy of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST).To overcome this negative effect,a third order Higher Order Sliding Mode (HOSM) controller is proposed.The key part of this approach is to design an appropriate observer which obtains the acceleration state.A nonlinear adaptive observer is proposed in which a novel polynomial model is applied to estimate the internal di... 相似文献
105.
Yi-Nan Zhu Hong Wu Hai-Ning Li Chen Cao National Astronomical Observatories Chinese Academy of Sciences Beijing China of Sciences China Graduate University of Chinese Academy of Sciences Beijing China Institute of Space Science Physics Sh ong University at Weihai Sh ong 《中国天文和天体物理学报》2010,10(4)
We analyze the feasibility of estimating the stellar mass of galaxies by mid-infrared luminosities based on a large sample of galaxies cross-identified from Spitzer SWIRE fields and the SDSS spectrographic survey.We derived the formulae to calculate the stellar mass by using IRAC 3.6 μm and 4.5 μm luminosities.The massto-luminosity ratios of IRAC 3.6 μm and 4.5 μm luminosities are more sensitive to the star formation history of galaxies than to other factors,such as the intrinsic extinction,metallicity and star formation rate.To remove the effect of star formation history,we used g-r color to recalibrate the formulae and obtain a better result.Researchers must be more careful when estimating the stellar mass of low metallicity galaxies using our formulae.Due to the emission from dust heated by the hottest young stars,luminous infrared galaxies present higher IRAC 4.5 μm luminosities compared to IRAC 3.6 μm luminosities.For most of type-Ⅱ AGNs,the nuclear activity cannot enhance 3.6 μm and 4.5 μm luminosities compared with normal galaxies.Star formation in our AGNhosting galaxies is also very weak,almost all of which are early-type galaxies. 相似文献
106.
Xu Zhou Zhen-Yu Wu Zhao-Ji Jiang Xiang-Qun Cui Long-Long Feng Xue-Fei Gong Jing-Yao Hu Qi-Sheng Li Gen-Rong Liu Jun Ma Jia-Li Wang Li-Fan Wang Jiang-Hua Wu Li-Rong Xia Jun Yan Xiang-Yan Yuan Feng-Xiang Zhai Ru Zhang Zhen-Xi Zhu National Astronomical Observatories Chinese Academy of Sciences Beijing China Nanjing Institute of Astronomical Optics & Technology National Astronomical Observatories Nanjing China Purple Mo... 《中国天文和天体物理学报》2010,10(3)
107.
制冷接收机是射电望远镜的核心设备,它是否正常工作直接决定望远镜观测的效果。制冷接收机的制冷温度和杜瓦真空度是反映接收机是否正常工作的最重要、最直接的指标之一。因此实现制冷接收机制冷温度和杜瓦真空度的远程实时监控,及时了解接收机是否正常工作对保证射电望远镜正常运行、提高观测效率有重要意义。为乌鲁木齐天文站25m射电望远镜1.3cm制冷接收机研制的一套基于单片机和以太网的数据采集和数据传输的远程监视系统,实现了制冷接收机制冷温度和杜瓦真空度的远程实时监控。该系统采用了美国ATMEL公司生产的8位单片机AVR ATmega16、Microchip Technology公司生产的ENC28J60以及MAXIM公司生产的MAX7219,实现对射电天文制冷接收机制冷温度和杜瓦真空度的数据采集,并利用以太网传输数据实现了远程实时监控接收机的制冷状态。阐述了以太网数据采集及远程监控电路的设计原理及其实现方法。该系统首次在国内大型射电望远镜上实现了对制冷接收机工作状态的远程实时监控,对于保证乌鲁木齐天文站25m射电望远镜1.3cm波段的观测效果有重要作用。 相似文献
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Shan-Jie Qian Xi-Zhen ZhangNational Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2004,4(1):37-50
The rapid polarization position angle swing of ~ 180?observed in QSO 1150+812 at 2cm by Kochenov and Gabuzda is quite a regular event. One interesting property of the event is that, during the time of the swing the polarized flux density remained almost constant. We suggest that such an event can be explained in terms of a relativistic thin shock propagating through a uniform helical magnetic field, giving rise to relativistic aberration effects as the transverse field component rotates. The model may also be applicable to other similar events in which variations in polarization are not accompanied by variations in total flux density. 相似文献
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