Primary nitrogen production at low Z     

Georges Meynet 《Astrophysics and Space Science》2002,279(1-2):183-186

Stellar models with axial rotation and very low metallicity Z, typical of the early star generations have been computed. These models account for the effects of rotation in the same way as previous grids which successfully reproduce the He- and N-enrichments observed at the surface of massive stars, and also the high numbers of red supergiants observed in low Z galaxies (Meynet and Maeder, 2000; Maeder and Meynet, 2001). At very low metallicity (Z = 0.00001, i.e. one two thousandth of the solar metallicity),these models naturally lead to the production of primary nitrogen. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Consolidation analysis of a cross-anisotropic homogeneous elastic soil using a finite layer numerical method     

Guo-Xiong Mei  Jian-Hua Yin  Jin-Min Zai  Zong-Ze Yin  Xiao-Li Ding  Guo-Fu Zhu  Lok Man Chu 《国际地质力学数值与分析法杂志》2004,28(2):111-129

This paper presents a finite layer procedure for Biot's consolidation analysis of layered soils using a cross-anisotropic elastic constitutive model. The program is first verified using published results. Then, using this program, the influences of cross-anisotropy on the immediate settlement, the final settlement, and the consolidation behaviour are investigated by changing one model parameter at one time. The results obtained using the cross-anisotropic elastic model are compared with results using an isotropic elastic model. It is found that the cross-anisotropy has very large influences on the immediate settlement, the final settlement, and the consolidation behaviour. Curves or tables of the immediate settlement coefficients, the final settlement coefficients, and the average degree of consolidation are obtained and presented in the paper. These curves or tables can be easily used to estimate the immediate settlement, the final settlement, and the consolidation settlement of a cross-anisotropic soil. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

动力锚在斜坡地基上的沉贯特性     

李云飞  韩聪聪  刘君 《海洋工程》2022,40(1):141-148

水上浮式结构都需要锚固基础来定位.动力锚依靠重力以自由落体的方式安装,是一种自安装锚固基础,具有安装过程简单高效的优点.通过1g模型试验研究了自行研制开发的板型动力锚在斜坡地基上的沉贯过程,分别考虑了基床坡度、锚柄方位和贯入速度对锚最终偏角的影响.结果表明:基床的坡度越大,锚的最终偏角也越大,但基床坡度对动力锚最终偏角影响有限,对动力锚的安装和承载能力影响较小.当贯入速度相同时,锚柄平行坡面时锚的最终偏角最小,锚柄指向坡外时锚的最终偏角最大;当基床坡度相同时,锚的贯入速度越大,锚的最终偏角越小.  相似文献   

GPS-Meteorology network in Wuhan region     

Yong Wang  Yanping Liu  Hong Xu  Xiaogang Hu  Lintao Liu  Houze Xu 《地球空间信息科学学报》2013,16(2):139-142

There are three aspects in the study of GPS meteorology network in the Wuhan region. The first is the comparison of the GPS precipitable water vapor between final ephemeris and ultra-rapid ephemeris for which the relative coefficient is 99.97 and the root mean squares is 0.048 mm. It can be concluded that ultra-rapid ephemeris can be used to get the GPS precipitable water vapor for the real-time prediction. The second is the comparison of precipitable water vapor of GPS stations and the distribution of water vapor in the Wuhan region is acquired. The change of GPS precipitable water vapor and rainfall in a rainfall process are compared and analyzed. The change of GPS precipitable water vapor can reflect and predict the process of rainfall.  相似文献   

伊通地堑深部软流圈的上涌及其对盆地发育演化的控制和影响   总被引：1，自引：0，他引：1  

余芳  孙家振  张玉芬 《地质科技情报》2009,28(3)

对广泛分布于伊通地堑边界断裂的新生代玄武岩稀土元素组成进行了岩石圈厚度反演,得到了新生代岩石圈厚度变化情况,并结合该区构造演化特征综合分析得出晚白垩世至更新世发生两期深部熔岩上涌：第一期发生于晚白垩世至古新世,软流圈上涌强度大,上涌至约50km,直接导致伊通盆地的断陷和沉降;第二期发生于中新世11．5～11．0Ma,持续时间短,软流圈上涌强度较弱,表现为隆起构造,对盆地断陷后期起改造作用,控制着莫里青地区尖山构造带的形成以及该地区沉降中心的迁移。  相似文献   

降水时间随机性对月总降水量的影响          下载免费PDF全文

苏京志 《大气科学学报》2019,42(1):109-116

降水量在时间分布上呈现较大的随机性,极端降水事件尤为如此。受此影响,月初(月末) 1～5 d之内的累积降水量很可能会超过当月总降水量的50%乃至更多。对1961—2017年中国2 400多站点资料统计分析结果发现,月初(月末) 1～5 d累积降水量对当月总降水量显著影响事件的出现频次,在季节和空间分布上都有鲜明特征。主要包括:1)月初累积降水量对秋冬季中各月的总降水量影响更大,月末累积降水量对1—4月的月总降水量影响较大。2)受月初累积降水量的影响,显著站点数在某些年份的某些月份出现极大值;受单次事件显著影响的站点数占全国总站点数的30%～50%,此即对应着一次全国大范围的极端降水事件。3)受月初(月末)累积降水量显著影响的站点空间分布随季节变化呈现出明显空间集聚特征。  相似文献   

Early Middle Triassic mafic dikes from the Baoshan subterrane,western Yunnan: implications for the tectonic evolution of the Palaeo-Tethys in Southeast Asia     

《International Geology Review》2012,54(8):976-993

The time of final closure of the Palaeo-Tethys and the Sibumasu-Indochina collision in Southeast Asia represents a major unresolved geologic problem. Here, we present zircon chronology, whole-rock elemental, Sr–Nd, and zircon Hf isotopic geochemistry for newly discovered mafic dikes from the northern segment of the Sibumasu terrane, to provide constraints on this issue. Zircon U–Pb data indicate that the dikes were emplaced at 240 ± 3 Ma. These are the earliest Mesozoic magmatic rocks reported so far in the Sibumasu terrane, the late Palaeozoic passive margin of the Palaeo-Tethys. They are subalkaline tholeiites, showing geochemical characteristics similar to those of enriched mid-ocean ridge basalts (E-MORBs). They have ⁸⁷Sr/⁸⁶Sr(t) ratios of 0.703161–0.703826, ?Nd(t) of +4.8 to +7.5, and zircon ?Hf(t) of +9.2 to +13.3, implying strong mantle depletion. They were derived by partial melting of asthenospheric mantle and underwent subsequent fractional crystallization and lithospheric assimilation. The geologic–petrologic evidence suggests that the mafic dikes were generated in a collisional setting, when suturing of the Baoshan and Simao subterranes (the two subterranes are part of the Sibumasu and Indochina terranes, respectively) occurred. These early Middle Triassic mafic dikes provide an upper limit for Sibumasu–Indochina collision. In conjunction with previous work, we conclude that the final closure of the Palaeo-Tethys and collision of the Sibumasu and Indochina terranes took place during the late Permian to Early Triassic.  相似文献   

综合管沟竣工测量数据处理的技术     

樊惠萍  张汉春 《地理空间信息》2011,(4):16-18

综合管沟近年来在广州得到越来越多的推广应用,因而研究综合管沟的数据信息系统显得十分必要。介绍了广州大学城、广州亚运城的综合管沟的基本情况,管沟类型,沟内管线分布,内业成图的图层设计、数据库设计,重点探讨了新出现的立交型综合管沟处理技术,实现了综合管沟数据库的科学管理。  相似文献   

Beta Gyres in Global Analysis Fields     

Sun-Hee KIM  H. Joe KWON  R. L. ELSBERRY 《大气科学进展》2009,26(5)

A three-component decomposition is applied to global analysis data to show the existence of a beta gyre, which causes Tropical Cyclone (TC) to drift from a large-scale environmental steering current. Analyses from the Global Data Assimilation and Prediction System (GDAPS) of the Korea Meteorological Adminis-tration (KMA), the Global Forecast System (GFS) of NCEP, and the Navy Operational Global Atmospheric Prediction System (NOGAPS) are used in this study. The structure of the beta gyre obtained in our anal...  相似文献   

利用Delphi 6实现单桩最终沉降量计算程序的跨平台开发     

唐益群  周玉石  黄雨  叶为民 《水文地质工程地质》2004,31(2):59-63

本文对Delphi6及其内部的VCL和CLX两个组件类库作了简要的论述,分析了这两个组件库的各自特点及相互之间的区别,对比了开发环境(Windows与Linux)的不同。根据CLX库完全支持跨平台的特性,说明了利用Delphi6实现应用程序的跨平台开发的具体方法和步骤,并提出了利用Delphi6进行跨平台开发的几点注意事项。最后,给出实现单桩承载力计算程序跨平台开发的关键源代码。  相似文献