K-shell photoionization cross-sections of N v and O vi     

E. Charro  K. L. Bell  I. Martin  A. Hibbert 《Monthly notices of the Royal Astronomical Society》2000,313(2):247-251

An 11-state R -matrix calculation is performed to obtain cross-sections for the photoionization of the 1s²2s ²S ground states of N  v and O  vi . For both ions at low photon energies, corresponding solely to the 2s photoionization cross-section, excellent agreement is found with previous calculations. For higher photon energies, permitting inner-shell photoionization of the 1s electron, excellent accord is found with the recent calculation of Nahar for O  vi , whilst for N  v resonance structure is found which previous calculations omitted.  相似文献   

Spectropolarimetric measurements of magnetic Ap and Bp stars in all four Stokes parameters     

G. A. Wade  J.-F. Donati  J. D. Landstreet  S. L. S. Shorlin 《Monthly notices of the Royal Astronomical Society》2000,313(4):823-850

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The spectral variations of the O-type runaway supergiant HD 188209     

G. Israelian  A. Herrero  F. Musaev  A. Kaufer  A. Galeev  G. Galazutdinov  E. Santolaya-Rey 《Monthly notices of the Royal Astronomical Society》2000,316(2):407-417

We report spectral time series of the late O-type runaway supergiant HD 188209. Radial velocity variations of photospheric absorption lines with a possible quasi-period of ∼6.4 d have been detected in high-resolution echelle spectra. Night-to-night variations in the position and strength of the central emission reversal of the H α profile occurring over ill-defined time-scales have been observed. The fundamental parameters of the star are derived using state-of-the-art plane-parallel and unified non-LTE model atmospheres, the latter including the mass-loss rate. The derived helium abundance is moderately enhanced with respect to solar, and the stellar masses are lower than those predicted by the evolutionary models. The binary nature of this star is not suggested either from Hipparcos photometry or from radial velocity curves.  相似文献   

South Segment of Minjiang Fault and Diexi Earthquake in 1933   总被引：3，自引：0，他引：3  

Qian Hong  Zhou Rongjun  Ma Shenghao  Li Xiaogang 《中国地震研究》2000,14(2):146-152

Diexi earthquake(M7.5)in 1933 is a great event that occurred at the east border of Qinghai- Xizang Plateau in the 20th century.There are obviously different opinions about the shape ofisoseismal lines and the genetic fault of this earthquke.Based on the study of the newlyfound north-south trending active fault and ground fissures of Diexi earthquake,this papertends to hold that,as the southward extension of Miujiang fault,this north-south trendingactive fault might be the genetic fault of this event.  相似文献   

GS型重力仪面板常数测定的研究   总被引：1，自引：0，他引：1       下载免费PDF全文

蔚晓利  苏乃秦  杨又陵  王云山 《地震工程学报》2000,22(2):172-176

系统分析了GS - 1 5 - 2 1 6重力仪多次在重力基线场标定的结果 ,并与厂家给出的面板常数进行对比 ,认为GS型重力仪的面板常数存在长期变化 ,应定期重新标定 ;检修或工作状态的变化也会引起面板常数的改变 ;面板常数是仪器测程的函数 ,必须分段标定以便拟合一条常数曲线 .  相似文献   

航空三线阵CCD影像测制城市数字正射影像   总被引：7，自引：0，他引：7  

王任享 《测绘工程》2000,9(1):1-8

提出了利用三线阵ＣＣＤ相机测制城市数字正射影像和建立三维模型与目标,开展航空直接获取数字影像的摄影测量。着重讨论了利用三线阵ＣＣＤ影像计算自由外方位无素并生成模型ＤＥＭ然后利用少量控制点建立地面－模型坐标转换关系,生成地面坐标系的ＤＥＭ和正射影像。  相似文献   

数字栅格地图的制作   总被引：10，自引：0，他引：10  

洪钢  张继贤  林宗坚 《测绘科学》2000,25(3):43-45,16

阐述了数字栅格地图制作的技术流程 ,并对技术流程的关键技术问题作了详细的阐述。从方法上解决了扫描过程中因阈值选择不当而出现的断线、粘连现象 ,从原理上介绍了几何纠正。最后从方法上介绍了彩色数字栅格地图的色彩归一化。  相似文献   

Positional error curves band of a planar line segment within GISs     

DAI Honglei LIU Wenbao CHEN Lansen 《地球空间信息科学学报》2000,3(1):70-73

1 Introductionffe well-for Meanboha Eno(MSRE),having advanop of talculang ndy,has bo widdyed to m the W of pont ednates inGIS' NY and gedop. N, it is Me tDtw the opiW eno Of a pont in whitw dirm-tion, while in praedce there is ned tO for the value ofghH or Of a trint in a peial boon SUCh asthe uha diW. The or curve of a glnt is ableto W twl the diAnbution wttiOn of twnt eno.ln an arbtw dich and it is the nd efhaive edfor dedbing forhed rm Of odnts in SUrVopng..mpneenng(Mithel, 1983…  相似文献   

基于栅格数据提取主骨架线的新算法     

杜世宏  杜道生  樊红  万幼川 《武汉大学学报(信息科学版)》2000,25(5):432-436

详细介绍了基于栅格数据的面状地物主骨架线的提取算法。该算法具有较快的处理速度和较强的适应性及内存需求少的优点 ,同时用该算法所提取的主骨架线为最优 (最长 )骨架线 ,可用于面状地物注记的自动配置。  相似文献   

    

Yu Xing  Dai Jin  Jiang Weimei  Fan Peng 《大气科学进展》2000,17(4):617-635

It is essential to learn the temporal and spatial concentration distributions and variations of seeding agents in cloud seeding of precipitation enhancement. A three–dimensional puff trajectory model incorporating a mesoscale nonhydrostatic model has been formulated, and is applied to simulating the transporting and diffusive characteristics of multiple line sources of seeding agents within super–cooled stratus. Several important factors are taken into consideration that affect the diffusion of seeding materials such as effects of topography and vertical wind shear, temporal and spatial variation of seeding parameters and wet deposition. The particles of seeding agents are assumed to be almost inert, they have no interaction with the particles of the cloud or precipitation except that they are washed out by precipitation. The model validity is demonstrated by the analyses and comparisons of model results, and checked by the sensitivity experiments of diffusive coefficients and atmospheric stratification. The advantage of this model includes not only its exact reflection of heterogeneity and unsteadiness of background fields, but also its good simulation of transport and diffusion of multiple line sources. The horizontal diffusion rate and the horizontal transport distance have been proposed that they usually were difficult to obtain in other models. In this simulation the horizontal diffusion rate is 0.82 m s⁻¹ for average of one hour, and the horizontal average transport distance reaches 65 km after 1 h, which are closely related to the background fields.  相似文献