排序方式: 共有36条查询结果,搜索用时 281 毫秒
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Xin-Fa Deng Yi-Qing Chen Ping Wu Cheng-Hong Luo Ji-Zhou He Mathematics Physics College Nanchang University Nanchang Management College Nanchang University Nanchang 《中国天文和天体物理学报》2006,6(4):411-420
From the Main galaxy data of the SDSS Data Release 4 (SDSS4), we have identified close galaxy pairs at neighbourhood radius R = 100 kpc by three-dimensional cluster analysis. Using the criterion that an "isolated galaxy pair" must be separated from its "nearest neighbor" by more than 500 kpc, we constructed an isolated galaxy pair sample of 1158 pairs. We also constructed a random pair sample by randomly selecting 1158 galaxy pairs from the Main galaxy sample, which has the same redshift distribution as the isolated galaxy pair sample, and in which the two components of any pair have the same redshifts. Comparative studies of luminosity and size between the members of the galaxy pairs are performed. We find and further confirm there is no tendency for paired galaxies to have similar luminosities or sizes. From the isolated pair sample we also selected a subsample with the magnitude limit of the primary raised by 2 magnitudes, so as to include pairs in which the secondary is 2 magnitudes fainter than the primary. This subsample contains 82 pairs. A random pair sample is similarly constructed. 相似文献
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YANG Dong-hong YANG Xue-xiang CHEN Dian-you College of Geo-Exploration Science Technology Jilin University Changchun Jilin China National Astronomical Observatories Chinese Academy of Science Beijing Changchun Jilin China College of Mathematics Science Jilin University Changchun Jilin China 《东北亚地学研究》2005,(Z1)
A calculation formula on spherical pattern of Qinghai-Tibet plateau moving model is established, Tibet massif moves norward by east in speed of 28 mm/a, Ganshu-Qinghai massif moves to northeast in speed of 15 mm/a, Qomolangma Feng moves northward by a few east in speed of 35 -42 mm/a. The low latitude perimeter is longer than the high latitude perimeter. When the Tibet massif moves northward, its latitude perimeter must be contracted and the Tibet massif must move eastward by Coriolis. Coriolis force is inertial in earth rotation. It makes the fall body turning to east and the rising block turning westward. In the Northern Hemisphere, it makes the northward body turning to east and the southward block turning to west. This is the reason why the tectonic zones of western Pacific are different from those of eastern Pacific. 相似文献
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Numericalanalysisoftheinteractionofsoil┐structureunderearthquakeloadingGEN-DEZHANG1)(章根德)SHU-CHENGNING2)(宁书成)1)InstituteofMe... 相似文献
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在电离层局部地区球对称假设下,推导了利用双频和单频无线电掩星观测数据,反演电离层电子密度剖面的两种方法. 双频反演的误差来自于载波相位的观测误差,单频反演误差则主要由伪距的观测精度决定. 由于载波相位测量精度比伪距测量精度高两个量级,因此双频反演的精度一般比单频反演的高些. 不过,两载波信号L1和L2之间的传播路径差异会给双频方法带来误差. 利用三维射线追踪的程序模拟的无线电掩星数据来评估这些方法,结果表明,反演出的电离层剖面与给定的模式电离层非常吻合,验证了两种方法的可靠性和准确性. 将这两种反演方法应用于处理实测的GPS/MET掩星观测数据,均能获取合理的电离层剖面信息. 且单频方法得到的反演剖面与双频方法相当一致, 这为利用LEO星载单频GPS接收机进行电离层掩星观测提供了理论基础. 相似文献
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Xuexiang Yang Dianyou Chen . College of Geo-exploration Science Technology Jilin University Changchun China . National Astronomical Observatories Chinese Academy of Sciences Beijing China . College of Mathematics Science Jilin University Changchun China 《东北亚地学研究》2003,(2)
At the beginning of the 21st century, the world is facing too many natural and artificial disasters, and man is also facing various decisions difficult to be made. The evidence for the earth warming-up is more clear year by year and natural disaster occurs frequently and economic loss in miserable situation, moreover, the evil consequence from the lose of control technologically, overage development is more serious year after year and the daily ecological envi-ronment of man is trending toward… 相似文献
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Xin-Fa Deng~ Yi-Qing Chen~ Qun Zhang~ Ji-Zhou He~ Mathematics Physics College Nanchang University Jiangxi Management College Nanchang University Nanchang 《中国天文和天体物理学报》2006,6(1):35-42
We study the super-large-scale structures in the Sloan Digital Sky Survey by cluster analysis,and examine the geometry and the properties of the member galaxies.Two subsamples are selected from the SDSS,Subsample 1 at the celestial equator and Subsample 2 further north.In Subsample 1 we discover two compact super-large-scale structures:the Sloan Great Wall and the CfA Great Wall.The Sloan Great Wall,located at a median redshift of z=0.07804,has a total length of about 433 Mpc and a mean galaxy density of about six times that of the whole sample. Most of its member galaxies are of medium size and brightness.The CfA Great Wall, located at a median redshift of z=0.03058,has a total length of about 251 Mpc and includes large percentages of faint and small galaxies and relatively fewer early-type galaxies. 相似文献
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Christopher A.Tout 《中国天文和天体物理学报》2007,(2)
Based on previous works of OPAL, we construct a series of opacity tables for various metallicities Z=0, 0.000 01, 0.000 03, 0.000 1, 0.000 3, 0.001, 0.004, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.1. These tables can be easily used in Eggleton's stellar evolution code in place of the old tables without changing the code. The OPAL tables are used for log10(T/K) > 3.95 and Alexander's for log10(T/K) < 3.95. At log10(T/K) = 3.95, the two groups' data fit well for all hydrogen mass fractions. Conductive opacities are included by reciprocal addition according to the formulae of Yakovlev and Urpin. A comparison of 1 and 5 M models constructed with the older OPAL tables of Iglesias and Rogers shows that the new opacities have most effect in the late stages of evolution, the extension of the blue loop during helium burning for intermediate-mass and massive stars. 相似文献
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3维离散数据四面体快速生成算法研究 总被引:6,自引:2,他引:6
文中系统地研究了使用逐点插入算法构建3维离散数据四面体模型中的几个关键问题,提出了动态创建和维护四面体拓扑关系的方法,建立了快速确定点在四面体中的算法原理及空外接球判断法则的简易表达式,实验分析证明本算法有着较高的执行效率,算法复杂度与点数几乎成线性关系。 相似文献