Stellar evolution models for Z = 0.0001 to 0.03     

Onno R. Pols  Klaus-Peter Schro¨der  Jarrod R. Hurley  Christopher A. Tout  & Peter P. Eggleton 《Monthly notices of the Royal Astronomical Society》1998,298(2):525-536

We have calculated a grid of empirically well tested evolutionary tracks with masses M between 0.5 and 50 M⊙, spaced by approximately 0.1 in log M , and with metallicities Z  = 0.0001, 0.0003, 0.001, 0.004, 0.01, 0.02 and 0.03. We use a robust and fast evolution code with a self-adaptive non-Lagrangian mesh, which employs the mixing-length theory but treats convective mixing as a diffusion process, solving simultaneously for the structure and the chemical composition. The hydrogen and helium abundances are chosen as functions of the metallicity: X  = 0.76 − 3.0 Z Y  = 0.24 + 2.0 Z .   Two sets of models were computed, one without and one with a certain amount of enhanced mixing or 'overshooting'. This amount has been empirically chosen by means of various sensitive tests for overshooting: (1) the luminosity of core helium burning (blue loop) giants of well-known mass, (2) the width of the main sequence as defined by double-lined eclipsing binaries with well-measured masses and radii, and (3) the shape and implied stellar distribution of isochrones of various open clusters. The first two tests have been the subject of previous papers, the third test is discussed in this paper. On the basis of these tests, we recommend the use of the overshooting models for masses above about 1.5M ⊙.   We describe here the characteristics of the models, the procedure for constructing isochrones for arbitrary age and metallicity from the models, and the performance of these isochrones for several intermediate-age and old open clusters. All original models are available in electronic form and we describe the means by which they may be obtained.  相似文献   

极射赤平投影中的数学方法   总被引：10，自引：0，他引：10  

钱辉  董火根 《高校地质学报》1997,3(3):328-337

本文提供了严格依据赤平投影原理并利用空间解析几何知识推导出的公式计算方法，可以写出已知产状的线或面的赤平投影方程，也能计算两线所共的面，两面的交线，线或面之间的夹角以及它们的平分线或平分面，可以进行真倾斜和视倾斜的换算，倾斜和侧伏的换算；模拟线面绕轴的旋转以及恢复节理的原始产状；最后阐述用计算机进行节理统计和绘制极点等密图的原理。所用的向量表示方法直观表达了相关构造要素之间的空间关系，可用于计算机辅助教学，也能用于生产实践，精度可达0.01°。  相似文献   

N—P—K复肥四元体系KCl—KH_2PO_4—CO（NH_2）_2—H_2O在     

张逢星  魏小兰  崔斌  马亚军  郭志箴 《盐湖研究》1996,(1)

基于Ｎ—Ｐ—Ｋ三元复肥的物理化学基础．首次测定了四元体系ＫＣｌ—ＫＨ２ＰＯ４—ＣＯ（ＮＨ２）２在２９８．２Ｋ时的溶度及饱和溶液的折光率，绘制了体系的溶度图和折光率──组成图。该体系的溶度图属低共饱型，平衡固相为组份化合物，低共饱点组成为：１００ｇ饱和溶液中．ＫＣｌ１３．３１ｇ，ＫＨ２ＰＯ４３．３３ｇ，ＣＯ（ＮＨ２）２４７．２６ｇ，Ｈ２Ｏ３６．１０／１０ｇ。  相似文献   

盐水体系热力学平衡态和非平衡态相图   总被引：2，自引：0，他引：2  

高世扬  夏树屏 《盐湖研究》1996,4(1):53-58

在对海水Ｎａ＋、Ｋ＋、Ｍｇ（２＋）／／ＣＩ－、ＳＯ４（２－）－Ｈ２Ｏ体系在２５℃时或室温条件下采用合成复体法得到的平衡溶解度相图，蒸发结晶方式得到的蒸发相和采用过饱和溶液封闭静置结晶法得到的过饱和区相图进行对比分析，把它们划分成两种类型，热力学平衡态和非平衡态相图。对这两类相图关系进行探讨基础上认为，热力学非平衡相图主要是由于同一种盐在水溶液中是双粒子形式共存而引起过饱和溶解度现象所致。  相似文献   

旋转针锥光下一光轴出露时快速测定2V的图解     

高凡 《矿物学报》1988,(2)

为了简化旋转针锥光下一光轴出露时测定2V的赤平投影法的绘图手续,设计了本图解,只要测取θ,R,R′与φ四值,就能更快地求得2V值。  相似文献   

Li-(Mg、Zn、Ni)钒酸盐三元体系相关系和结晶化学     

王辅亚 《矿物学报》1989,(3)

对Li-(Mg、Zn、Ni)钒酸盐系统在500—800℃的相图研究发现:(Mg、Zn、Ni)V_2O_6和(Mg、Zn、Ni)_2V_2O_7,二个系统中都有两个主要固溶体,一个以NiV_2O_6(或Ni_2V_2O_7)为主结构,另一个在MgV_2O_6-ZnV_2O_6间形成完全连续型,Mg_2V_2O_7-Zn_2V_2O_7间为MgZnV_2O_7结构型。(Mg、Zn、Ni)_3V_2O_8系统中,整个就是一个固溶体,而Li(Mg、Zn、Ni)VO_4系统中,端员组分相互间也形成不同的固溶体。  相似文献   

Fluid-rock interaction in some shear zones from the Pyrenees   总被引：4，自引：0，他引：4  

A. M. McCAIG 《Journal of Metamorphic Geology》1984,2(2):129-141

Abstract Mylonites from shear zones cutting Hercynian gneisses in the central Pyrenees have been studied in thin section and using the electron microprobe. The shear zones contain retrogressive greenschist facies assemblages implying introduction of an aqueous fluid during deformation in the zones. Textural evidence suggests that fluid-rock interaction occurred throughout the active life of the shear zones.
Whole-rock chemical changes during deformation are documented in a variety of mylonitic lithologies and retrogressed country rocks. The overall effect was to reduce chemical differences between lithologies. Activity diagrams show that this would be expected if a hydrous fluid was circulating between different lithologies during deformation. In most cases fluid/rock ratios were relatively small resulting in gradual chemical changes and repeated recrystallization. 'Open-system'behaviour with reduction in the number of phases is seen in some granite mylonites, suggesting focusing of fluid movement in parts of the shear zones. Continual fluid-rock interaction may have led to reaction-enhanced ductility in the shear zones over a long period of time. The source of fluid is uncertain, but may be related to underthrusting of material beneath the area investigated.  相似文献   

Enrichment characteristics of radioelements in various types of rock from Sambalpur district,Orissa, India     

A. A. P. S. R. Acharyulu  B. Sreenivasa Murty  B. K. Bhaumik 《Journal of Earth System Science》2004,113(3):321-352

Over the years a large number of rock samples were collected by the explorationists of Atomic Minerals Directorate for Exploration and Research (AMD), Department of Atomic Energy from Sambalpur district, Orissa, India. The variation of uranium enrichment with various types of rock in these samples was studied with an aim to help quick reviewing of toposheets in case of newly taken up areas, for uranium exploration. The radioelements U, Th and K determined for these samples are plotted in ternary diagrams for classifying them as being uraniferous or thoriferous with respect to various type of rocks, keeping the total natural content of radioelements (expressed by eUP₃O₈) as a parameter. In this study it is seen that samples of quartzofeldspathic breccia type are enriched in uranium irrespective of their further sub classification and eU₃O₈ content. Granites are enriched in thorium when eU₃O₈ < 100 ppm and are enriched in uranium when eU₃O₈ > 100 ppm. A database prepared for this purpose may be useful for reviewing toposheets in future  相似文献   

SURFER在地球化学图制图中的应用   总被引：13，自引：0，他引：13  

赵荣军  和向丽 《物探与化探》2004,28(2):167-169

用SURFER的9种网格化模型分别绘制了等值线图,通过对比认为径向基本函数法对数据网格化后绘制的图形与手绘图形元素异常与分布趋势基本一致,作为地球化学图绘制的网格化模型效果最佳;提出了用采样点位图自动计算坐标—SURFER绘制等值线—MAPGIS处理成图的工作流程。  相似文献   

尾矿坝治理技术   总被引：2，自引：0，他引：2  

董翠兰  季学培 《世界地质》2003,22(2):172-175,180

尾矿坝在矿山环境的保护和治理中起到很大的作用，它主要应用于堆放和处理矿山生产所带来的废渣、废水等污染物质，而坝体浸润线过高会影响尾矿坝的稳定性。尾矿坝治理技术众多，重点介绍了管井法降水、垂直水平自流排渗法、水平自流排渗法、辐射井排渗法等。在结合实例讨论的基础上，综合分析了不同方法的优、缺点，并提出了其应用范围以及其在应用中应注意的技术问题。  相似文献