一种亮星识别算法及其在天文定向中的应用     

詹银虎  郑勇  张超  李铸洋  张中凯 《测绘学报》2015,44(3):257-263

基于全站仪对任意亮星的观测采样,提出了一种利用高度角序列和水平角速率进行联合匹配的任意亮星识别算法。通过引入天体地平坐标计算程序,算法可正确辨别行星和恒星。本文分析了任意亮星高度角和水平角速率的观测误差和计算误差,以此给出了匹配阈值条件的设定依据,并在此基础上制定了有效的匹配策略。仿真计算及实际观测试验均表明,该算法具有100%的识别成功率,远优于现有算法。将此算法应用于任意亮星天文定向,定向结果的内符合精度达到2″,外部检核精度达到1.6″。采用多颗任意亮星进行定向,可有效减弱由测站位置误差引入的定向系统误差,提高绝对定向精度。本文提出的天文定向适用于多云及雾霾天气。  相似文献   

Different Features of Jets and Isotropic Fireballs in Gamma-ray Burst Phase     

Yun-Ming Dong Lan-Wei Jia Xiao-Hong Zhao Yunnan Astronomical Observatory/National Astronomical Observatories  Chinese Academy of Sciences  Kunming  Graduate University of Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2006,6(1):69-76

We investigated physical quantities including the spectrum,emission lines and pulse profiles expected from a uniform jet,a spherical fireball and the 1/Γ region (the portion of the spherical fireball with opening angle 1/Γ)in the prompt emission phase,after taking into consideration of the Doppler effect under the fireball frame- work.Our study shows that:a)for these physical quantities the spherical fireball and the uniform jets do not present obvious differences,so we cannot use these to distinguish a spherical fireball from a uniform jet;b)for the spherical fireball and a uniform jet,the observed quantities mainly come from the 1/Г region,so we can simply use the 1/Г region in approximate calculations;c)broadening of emission lines is a general phenomena,which mainly comes from the curvature effect;d)the 1/Γ region plays different roles in different frequency ranges,and the radiation from the 1/Γ region is greater in the higher than in the lower frequencies.  相似文献   

CCD Photometry of Asteroid （147） Protogeneia     

Xi-Liang Zhang  Xiao-Bin Wang  Li-Yun Zhang National Astronomical Observatories / Yunnan Observatory  Chinese Academy of Sciences  Kunming  Graduate School of Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2006,6(6):729-732

We measured the light-curve of the asteroid (147) Protogeneia in November 2004, with a CCD detector attached to the 1-meter telescope at the Yunnan Observatory, China. The synodic period and maximum amplitude of (147) at this apparition are 7.852 hours and 0.25 mag, respectively. The value of a/b for (147), from a preliminary estimation, is not less than 1.26:1.  相似文献   

An Efficient High-Resolution Shock-Capturing Scheme for Multi-Dimensional Flows I. Hydrodynamics     

Cong Yu National Astronomical Observatories / Yunnan Astronomical Observatory  Chinese Academy of Sciences  Kunming  Graduate School of Chinese Academy of sciences  Beijing 《中国天文和天体物理学报》2006,6(6):680-688

Many problems at the forefront of theoretical astrophysics require a treatment of dynamical fluid behavior. We present an efficient high-resolution shock-capturing hydrody-namic scheme designed to study such phenomena. We have implemented a weighted, essentially non-oscillatory (WENO) scheme to fifth order accuracy in space. HLLE approximate Riemann solver is used for the flux computation at cell interface, which does not require spectral decomposition into characteristic waves and so is computationally friendly. For time integration we apply a third order total variation diminishing (TVD) Runge-Kutta scheme. Extensive testing and comparison with schemes that require characteristic decomposition are carried out demonstrating the ability of our scheme to address challenging open questions in astrophysics.  相似文献   

Magneto-induced Line Broadening of Magneto-sensitive Lines in Solar Magnetized Atmospheres     

Zhong-Quan Qu  Shuai Wang  Cheng-Lin Xu  XiaoYu Zhang  Ming-Guo Sun  Chun-Lan Jin National Astronomical Observatories/Yunnan Astronomical Observatory  Chinese Academy of Sciences  Kunming  zqqu@vip.km.net Graduate School of the Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2005,5(4):426-432

We analyze the spectral line broadening of those magneto-sensitive lines in solar magnetized atmospheres. The broadening at the line wings is due to the increase of the effective width of energy levels involved in Zeeman splitting, and the broadening at the line core also originated in Zeeman splitting under the condition that the Zeeman components are mixed. Therefore, the magnetoinduced or Zeeman broadening take effects on the whole line. The observed Stokes parameter data in a sunspot and outside it acquired by Solar Stokes Spectrum Telescope (S3T) are analyzed for the demonstration of this mechanism, and the Zeeman broadening rates are calculated for FeI6302.5 under some assumptions. Our result shows that the broadening is increased as the magnetic field strength becomes stronger, but the rate of increase at the line core is decreased as the field strength increases, while the rate at the wing does not show such an obvious regularity. The broadening is more effective in the line core than in the wings.  相似文献   

计算空间VLBI天线面有效截面程的数学模型     

郑勇  钱志瀚 《中国科学院上海天文台年刊》1992,(13):140-144

本推导建立了计算空间VLBI天线面有效截面的数学模型，它将适用于确定空间VLBI站轨道所需的太阳光压、大气阻力、地球反照压等非引力摄动模型中面质比的计算。  相似文献   

Analysis on the decadal scale variation of the dust storm in North China   总被引：3，自引：0，他引：3  

KANG Dujuan  & WANG Huijun . NZC/LASG  Institute of Atmospheric Physics  Chinese Academy of Sciences  Beijing  China  . Environmental Fluid Mechanics Laboratory  Stanford University  Stanford CA  USA 《中国科学D辑(英文版)》2005,48(12):2260-2266

Dust storm is a disastrous weather that can cause serious environmental consequences and hazards. It causes excessive soil mass and nutrient loss in source areas, and air pollution in deposition area, which result in bad influence on agriculture, industry, traffic, and peoples’ daily life[1-4]. Dust storm can also affect the thermal balance of planetary radiation and then lead to meso- to macroscale climatic modification[5-7]. North- west China and North China are two high-frequency centers …  相似文献   

安徽绩溪伏岭岩体隆升时代的磷灰石裂变径迹证据   总被引：1，自引：0，他引：1  

郑勇  余心起  王德恩  汪诚 《地质论评》2009,55(3):385-394

安徽绩溪伏岭岩体位于安徽省南部、黄山花岗岩体的东部。伏岭岩体裂变径迹（AFT）热年代分布于51±5～68±7 Ma之间,围限径迹长度为11.9～12.9μm。岩体形成之后,所在山系经历了速率波动较大的隆升过程,至55 Ma期间为一加速隆升过程,到55 Ma时速度达到最大的73 mm/ka;随后速度减缓,54 Ma左右时的平均抬升速率为60 mm/ka;54～51 Ma间又是一个快速加速隆升时期,到51 Ma时,速度达到70 mm/ka。研究区具有三个主要的冷却剥露阶段：130～116 Ma左右,冷却速率约为1.34℃/Ma;70～60 Ma左右,进入第二个较为快速冷却阶段,冷却速率约为25℃/Ma;在7～8 Ma左右发生突然加剧冷却事件,持续至今,速率达到8℃/km。总体来说,伏岭岩体经历了速率逐渐增加的冷却过程。由于黄山山体与伏岭岩体在大地构造位置、岩性特征及侵入时间上具有很大的相似性,二者的隆升时代、速率以及抬升剥蚀量是大致相当的。  相似文献   

不同跨高比对多层钢框架内填混凝土深梁结构抗震性能影响          下载免费PDF全文

袁晓洒    张力    刘方    贾腾飞  贾星亮   《世界地震工程》2021,(1):034-40

为了研究不同跨高比多层钢框架内填混凝土深梁结构的抗震性能,在钢框架内填混凝土深梁滞回性能试验的基础上,利用ABAQUS对六层纯钢框架（结构一）、钢框架内填跨高比为2混凝土深梁结构（结构二）和钢框架内填跨高比为0.75混凝土深梁结构（结构三）进行弹塑性时程分析。结果表明:内填混凝土深梁使结构整体刚度明显增大;在地震波的作用下,结构二的最大顶点位移降低可达58.3%,结构三的最大顶点位移降低可达89.3%,内填混凝土深梁,结构的抗侧移性能得到了极大改善,且随着深梁跨高比的减小而大幅度提升;结构二滞回曲线饱满,呈现纺锤形,混凝土深梁充分起到了第一道防线作用。经济合理的钢框架内填混凝土深梁结构具有一定的工程应用价值。  相似文献   

粘滞阻尼耗能连梁的超高层结构减震性能研究          下载免费PDF全文

隋    伍振平  申泽波  杨仁猛  罗峥 《世界地震工程》2021,(1):066-77

连梁作为剪力墙结构中的抗震第一道防线,其承载力和耗能能力对整体结构的抗震性能有重要影响。本文提出在连梁中附设粘滞阻尼器,利用阻尼器发生竖向剪切变形而耗能。结合实际工程研究粘滞阻尼耗能连梁的性能,采用ETABS和PERFORM-3D软件对粘滞阻尼耗能连梁结构与传统连梁结构进行有限元模拟对比分析,并对粘滞阻尼耗能连梁的各项最优参数进行研究。结果表明:粘滞阻尼耗能连梁充分发挥耗能作用,整体结构具有良好的抗震性能,与传统连梁结构相比,主体结构的弹性耗能得到明显降低。平面布置方式、竖向布置方式、阻尼器参数的选取对附设粘滞阻尼耗能连梁的框架-核心筒结构减震效果影响较大,合理选择这些参数可以使耗能结构减震效果最优。  相似文献