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841.
W. Schmidt 《Astronomische Nachrichten》2003,324(4):374-375
Observations nowadays reveal more and more details about the small‐scale structure of the penumbra and umbra. Recent measurements of the motions in the penumbra indicate that (i) the Evershed flow is confined to a thin photospheric layer and (ii) the material rises from and sinks to subphotospheric layers within the penumbra. This flow pattern solves the question of the mass budget of the Evershed flow in a natural way. The nature of umbral dots and their role for the spot's energy budget remains unclear, since they are obviously unresolved even in the best existing measurements. 相似文献
842.
843.
嵩溪是一个新发现的大型银(锑)矿,位于永梅拗陷南段寨岗上火山沉积盆地的边缘。前人多认为其形成与火山活动有关,主要有海底基性火山喷流和中低温火山热液充填等成因观点。但矿物流体包裹体超高真空四极气相质谱系统测定表明其中存在多种轻烃气体,它们主要由C1~4饱和烷烃组成,仅含微量C2~4不饱和烯烃和芳烃,说明成矿过程基本未受到岩浆作用的影响。这些轻烃气为微生物作用成因和沉积岩围岩中Ⅱ类干酪根热解成因的混合气体。从有机气体组成看,嵩溪矿床的成矿背景属裂谷环境。本文的研究从一个侧面支持了作者等提出的嵩溪银(锑)矿可能属沉积热卤水改造型矿床的看法。 相似文献
844.
845.
A. Collier Cameron J.-F. Donati 《Monthly notices of the Royal Astronomical Society》2002,329(1):L23-L27
We present measurements of the rotation rates of individual starspots on the rapidly rotating young K0 dwarf AB Doradus, at six epochs between 1988 December and 1996 December. The equatorial rotation period of the star decreased from 0.5137 to 0.5129 d between 1988 December and 1992 January. It then increased steadily, attaining a value of 0.5133 d by 1996 December. The latitude dependence of the rotation rate mirrored the changes in the equatorial rotation rate. The beat period between the equatorial and polar rotation periods dropped from 140 to 70 d initially, then rose steadily. The most rigid rotation, in 1988 December, occurred when the starspot coverage was at a maximum. The time-dependent part of the differential rotation is found to have , which should alter the oblateness of the star enough to explain the period changes observed in several close binaries via the Applegate mechanism. 相似文献
846.
阴山超大型硫化物矿床形成的有利条件 总被引:1,自引:0,他引:1
阴山中元古代成矿带(狼山 渣尔泰山)属于华北地台元古宙巨大成矿带的西段,产有多处硫铁 多金属矿床,一些已经达到超大型矿床的规模。它们形成的时代和地质环境具显著的热水沉积成矿的特征,可与世界中元古代SEDEX对比。已经判别出成矿盆地及热水通道等。充足的物质来源、巨大的热源、热水系统演化的完整性、成矿盆地极好的封闭性保证了同生期成矿的高强度,造山期的后生作用也有明显叠加 改造作用 相似文献
847.
AnalysisofthegeothermalvortexestriggeringtheXingtaiearthquakein1966MAOCANGTANG(汤懋苍)XIAOQINGGAO(高晓清)LanzhouInstituteofPlate... 相似文献
848.
通过对株洲县湾塘-王家洲区段地层、构造、水文、岩浆岩的研究,探讨了本区温泉的形成机制,根据温泉的特征,将本区温泉分为低温温泉和中温温泉两类;运用水文地质的研究方法对本区的地下热水水质、水温和可供开采有补给保证的地下热水资源量进行了科学的分析计算和概括;从经济和社会效益角角对本区温泉的开发前景进行了探讨。 相似文献
849.
P. Vivekananda Rao M. B. K. Sarma B. V. N. S. Prakash Rao 《Journal of Astrophysics and Astronomy》1991,12(3):225-263
Results of analysis of photoelectric observations of the RS CVn eclipsing binary WY Cancri in the standard passbands ofUBV during 1973-74, 1976-79 and inUBVRI during 1984-86 are reported. A preliminary analysis of the eclipses suggested the primary eclipse to be transit. A study
of the percentage contribution of the distortion wave amplitudes in all the colours with respect to the luminosities of both
components, showed the hotter component to be the source of the distortion wave. The clean (wave removed) light curves of
different epochs have not merged, suggesting residual effects of spot activity. The reason for this is attributed to the presence
of either (1) polar spots or (2) small spots uniformly distributed all over the surface of the hotter component. This additional
variation is found to have a periodicity of about 50 years or more. The distortion waves in yellow colour are modelled according
to Budding’s (1977) method. For getting the best fit of the observations and theory, it was found necessary to assume three
or four spots on the surface of the hot component. Out of these four spot groups, three are found to have direct motion with
migration periods of 1.01, 1.01 and 2.51 years while the fourth one has a retrograde motion with a migration period of 3.01
years. From these periods and the latitudes of the spots derived from the model a co-rotating latitude of 4ℴ is obtained.
The temperatures of these spots are found to be lower than that of the photosphere by about 700ℴK to 800ℴK. Assuming the light
curve of 1985-86, which is the brightest of all the observed seasons, to be least affected by the spots, the light curves
of the other seasons are all brought up to the quadrature level of this season by applying suitable corrections. The merged
curves in theUBVRI colours are analysed for the elements by the Wilson-Devinney method. This analysis yielded the following absolute elements:
相似文献
850.
The procedure of assessment of structural fatigue strength of an offshore floating production and storage and offloading unit(FPSO) in this paper. The emphasis is placed on the long-term prediction of wave induced loading, the refined finite element model for hot spot stress calculation, the combination of stress components, and fatigue damage assessment based on S-N curve. 相似文献
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