s-过程核合成参数化研究与铅星产生的物理条件

介绍了重元素核合成理论和一些最新的AGB星核合成模型,利用参数化方法计算了AGB星核合成的产量,得到了不同中子数密度(初始金属丰度)、脉冲周期、重叠因子下[Pb/Ce]的数值,在此基础上讨论了铅星产生的物理条件,进而解释了已观测到的各金属丰度下AGB星Pb丰度离散的问题.     

强钡星和弱钡星的比较

利用星风吸积模型,计算了钡星的初始质量和AGB伴星的金属丰度对弱钡星和强钡星超丰因子的影响,计算了弱钡星和强钡星重元素(Y,Nd)丰度随轨道周期终值的变化,并和观测值作了比较.由此得出结论:强钡星和弱钡星的区别主要是金属丰度不同(即年代不同),而不是轨道距离;弱钡星和强钡星相比,属于较年轻、质量较大、金属丰度较丰富的星族;这就意味,s-元素的核合成在低金属丰度星族更有效产生.     

外赋AGB星s-元素丰度与金属丰度的关系

以内禀AGB星重元素丰度的演化和外赋AGB星重元素超丰的计算为基础,计算了外赋AGB星较重s-元素丰度、较轻s-元素丰度、重s-元素和s-元素丰度的比与平均中子辐照量的关系,从理论上定量解释了外赋AGB星s-元素与金属丰度的逆相关性.     

S-过程元素丰度分布规律的研究

利用指数辐照理论的解析解研究了AGB星S过程元素的丰度分布规律 .结果表明 ,在低金属丰度下 ,AGB星核合成产量强烈依赖于金属丰度 ,但如果将Sm( 88相似文献   

AGB星表面重元素丰度:初始丰度的影响

采用新的s-过程核合成模型和分叉s-过程反应通道,分别取太阳系重元素丰度,太阳系纯r和s-main分量的重元素丰度作初值,计算了太阳金属丰度3MTP－AGB星表面重元素丰度,结果表明,不同初值得到不同的表面元素丰度分布。     

重金属星的形成

重金属星是重金属丰度超丰的星,重金属是通过中子俘获形成的,中子俘获有两种过程,快中子俘获过程（r-过程）,慢中子俘获过程（s-过程）,AGB星是产生重金属的重要产地,贫金属的AGB星容易形成铅星,这已获得观测的支持。     

水平分支星壳层质量的分布与金属丰度的关系研究

水平分支星的壳层质量决定了恒星在水平分支的位置,进而决定了星团的水平分支形状。利用MESA恒星演化程序研究了球状星团水平分支星的壳层质量随着金属丰度变化的关系。我们发现,由于不透明度以及零年龄主序质量的减小,低金属丰度球状星团中的水平分支星往往拥有更薄的壳层质量和更高的有效温度。同时,随着金属丰度的增加,产生蓝端水平分支星的壳层质量空间变小,这说明金属丰度低的球状星团更容易产生蓝端水平分支星。     

物质吸积的外赋AGB星参数化模型

以单星的参数化慢中子俘获过程核合成模型为基础,提出了包含物质吸积的外赋AGB星参数化模型:在双星系统中,采用稳定的洛希瓣物质转移率.通过逐次脉冲将主星外包层的物质转移给伴星,伴星表面的物质经多次混合而最终形成外赋AGB星.此外,利用此模型较好地拟合了HD201626和HD196944的表面元素丰度.     

星系中子辐照量分布函数

先引入随时间t变化的星系中子辐照量分布函数gρal(t,τ)描述各演化阶段星系s-过程核素丰度的分布规律.利用星系化学演化的三成分模型导出星系中子辐照量分布函数的演化方程,从而建立星系的中子辐照量分布函数gρal(t,τ)与AGB星的中子辐照量分布函数ρAGB(τ)之间的关系.取AGB星中子辐照量为指数分布,当取t=t⊙时,得到了太阳系的中子辐照量分布Sρun(τ).     

球状星团热水平分支星形成的机制研究

球状星团中热的水平分支星包括极端水平分支星和蓝勾星,他们的形成机制目前仍然不清楚。我们利用MESA恒星演化程序,在双星演化中考虑潮汐增强星风过程,研究主星在红巨星阶段丢失大量壳层质量并经历延迟氦闪后对热水平分支星的贡献。我们的研究结果表明,在潮汐星风作用下,双星演化导致的早期热氦闪能产生极端水平分支星,而双星演化导致的延迟氦闪能产生蓝勾星。而且,随着氦丰度的增加,产生蓝勾星的初始双星周期空间增大,这意味着初始氦丰度高的双星更容易产生蓝勾星。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.