The spectral investigation of seven HII regions in Kazarian galaxies     

V. Zh. Adibekyan 《Astrophysics》2008,51(1):58-68

Spectra from SDSS DR5 are used for a spectral study of seven HII regions in Kazarian galaxies. The abundances of helium and heavy elements, and also the quantity of ionizing stars and the star formation rate in these galaxies, are determined. The oxygen abundance, 12+log(O/H) lies between 7.94 and 8.35. The mean abundance ratios log(S/O), log(Ar/O), and log(Ne/O) are equal to −1.63, −2.37, and −0.78, respectively. For these HII regions, log(N/O) lies between −0.63 and −1.37. On an N/O-O/H diagram they occupy the same area as high excitation HII regions. In all likelihood the ages of the HII regions studied here exceed the 100–300 million years, required for the enrichment in nitrogen by intermediate-mass stars.. The star formation rate is one order as in the HII regions of spiral and irregular galaxies and ranges from 0.05 ÷ 0.81 M_⊙. year⁻¹. __________ Translated from Astrofizika, Vol. 51, No. 1, pp. 75–87 (February 2008).  相似文献   

Emission stratification in two-component HII regions with stellar wind     

K. V. Bychkov  T. G. Sitnik 《Astronomy Letters》2008,34(2):104-112

To explain the variety of observed optical emission stratification in the shells around Wolf-Rayet stars, we have calculated the nonstationary cooling of a homogeneous gas layer heated to a temperature (0.4–2) × 10⁵ K. We have assumed that the nebula is ionized by its central star and consists of a rarefied gas and a set of clouds with different densities through which adiabatic shock waves produced by the stellar wind propagate. Based on this model, we have determined the sequence in which the emission in Hα and in nebular oxygen lines appears. The Hα emission attributable to the electron-collision excitation of hydrogen atoms is produced earliest on the periphery of nebulae, the [O III] line emission follows next, and, finally, the Hα recombination emission is produced. The results obtained are in good agreement with the observational data.  相似文献   

刚体地球CIP轴的极移和岁差章动     

张捍卫  许厚泽  王爱生 《大地测量与地球动力学》2005,25(1):65-67

基于刚体地球极移和章动的联合动力学方程。给出了CIP轴的极移、岁差章动动力学方程,在顾及到5阶岁差章动力矩的情况下,给出了CIP轴的岁差章动表达式。通过推导发现。奇数阶引潮力位产生的岁差章动力矩使得黄经章动和交角章动出现了异向项(即：黄经章动出现了cos项,交角章动出现了sin项)。  相似文献   

两个大气环流模式SAMIL和BCC_AGCM对北半球冬季极涡振荡的模拟对比   总被引：1，自引：1，他引：1  

刘玉镇  任荣彩  何编 《大气科学》2012,36(6):1191-1206

基于与NCEP再分析资料的比较, 本文利用大气环流模式SAMIL和北京气候中心大气环流模式BCC_AGCM的1950～1999年的AMIP试验模拟数据, 对北半球冬季环流及平流层极涡振荡的模拟性能进行了评估分析。结果表明两个模式都可以再现北半球环流基本型以及环流振荡的主导模态。对冬季气候平均态的模拟, 两个模式模拟的热带—热带外温度梯度均偏大, 极夜急流偏强, 极涡偏冷偏强;100～20 hPa平均位势高度场谐波分析表明两个模式模 拟的行星波偏弱;气候平均的10 hPa极夜急流均存在1个月的季节漂移, 200 hPa副热带西风急流较NCEP偏弱。两个模式模拟的环流变化的主导模态均代表极涡振荡, SAMIL极涡振荡的强度大于BCC_AGCM, BCC_AGCM极涡振荡的频率要高于SAMIL。连续功率谱分析表明, NCEP资料中极涡振荡存在4.6个月的显著周期, 相应地, SAMIL中为5.5个月的显著周期, BCC_AGCM中为4.8个月。NCEP资料中的极涡振荡主要发生在12～3月, SAMIL模拟的极涡振荡主要发生在2～3月, BCC_AGCM模拟的极涡振荡主要发生在2～4月。  相似文献   

Simulation and evaluation of 2-m temperature over Antarctica in polar regional climate model     

XIN YuFei  BIAN LinGen  Annette RINKE & Klaus DETHLOFF 《中国科学:地球科学(英文版)》2014,57(4):703-709

The European Centre for Medium-Range Weather Forecasts Reanalysis ERA40,National Centers for Environmental Prediction(NCEP) 20th-century reanalysis,and three station observations along an Antarctic traverse from Zhongshan to Dome-A stations are used to assess 2-m temperature simulation skill of a regional climate model.This model(HIRHAM) is from the Alfred Wegener Institute for Polar and Marine Research in Germany.Results show:(1) The simulated multiyear averaged 2-m temperature field pattern is close to that of ERA40 and NCEP;(2) the cold bias relative to ERA40 over all of Antarctic regions is 1.8℃,and that to NCEP reaches 5.1℃;(3) bias of HIRHAM relative to ERA40 has seasonal variation,with a cold bias mainly in the summer,as much as 3.4℃.There is a small inland warm bias in autumn of 0.3℃.Further analysis reveals that the reason for the cold bias of 2-m temperature is that physical conditions of the near-surface boundary layer simulated by HIRHAM are different from observations:(1) During the summer,observations show that near-surface atmospheric stability conditions have both inversions and non-inversions,which is due to the existence of both positive and negative sensible heat fluxes,but HIRHAM almost always simulates a situation of inversion and negative sensible heat flux;(2) during autumn and winter,observed near-surface stability is almost always that of inversions,consistent with HIRHAM simulations.This partially explains the small bias during autumn and winter.  相似文献   

路基坡脚积水对多年冻土路基稳定性的影响研究进展     

胡晓莹  盛煜  李静  吴吉春  陈继  宁作君  曹元兵  冯子亮  王生廷 《冰川冻土》2014,36(4):876-885

多年冻土路基的稳定性很大程度上取决于其下伏多年冻土层的热稳定性. 当融雪、降雨或人为等外界因素形成的路基坡脚积水持续一段时间后,这些积水可能通过入渗对流换热、热边界侵蚀、补给冻胀水分等方式加剧或诱发多年冻土路基热稳定性的下降和丧失. 通过回顾国内外相关文献,从影响多年冻土路基稳定性的因素、积水对路基活动层冻融过程中水分迁移的影响、热融湖塘类积水对冻土路基的热影响、降雨和融雪积水入渗对冻土路基的热影响等方面,归纳总结了坡脚积水对多年冻土路基影响方面的研究进展;在此基础上,提出了对此问题进一步深入的研究展望和探讨.  相似文献   

寒区露天煤矿排土场边坡生态修复研究     

薛春晓  石龙  火明彩 《冰川冻土》2014,36(4):1026-1030

通过对寒旱区生态修复技术的集成创新,结合寒区露天煤矿排土场植物生长条件特点,提出了适合矿区边坡的生态修复技术. 选择典型煤矿排土场展开现场试验,观测人工种植植物的生长情况,并采用计算流体力学数值分析手段,对排土场边坡生态修复防止风力侵蚀和降雨冲刷的效果进行了分析. 结果表明：采用边坡穴植植物装置实施的排土场生态修复工程效果良好,施工1 a后其边坡植被覆盖度达到95%,且边坡植物群落较为稳定,有效地消除了该地区冬季的风力侵蚀和夏季的降雨冲刷,彻底解决了排土场的水土流失问题.  相似文献   

Analysis of the negative effects of groundwater exploitation on geological environment in Asia          下载免费PDF全文

ZHANG Jian-kang  WEN Xue-ru  GAO Yun  YUE Chen  YI Qing 《地下水科学与工程》2015,3(2):202-212

This paper summarizes the negative effects on geological environment caused by groundwater exploitation and its distribution. There are seven main types of the geological environment negative effects, which are generally as follows:(1) Constant decrease of groundwater level is mainly distributed in China(East Asia), India(South Asia), Tajikistan(Central Asia) and Saudi Arabia(West Asia);(2) land subsidence occurs mainly in eastern plains of East Asia and west Siberian Plain of North Asia;(3) seawater intrusion occurs mainly in China, Japan and South Korea in East Asia, Philippines and Indonesia in Southeast Asia, the Indian coastal areas in South Asia;(4) groundwater level decline caused by groundwater exploitation in oil fields;(5) mining collapse is mainly in 50° to 70° north latitude band;(6) the total area of karst collapse in China of East Asia is as much as 197.05 km~2; and(7) ground fracture is mainly distributed in the North China Plain, Fenwei Plain and the Yangtze River Delta. Asia can be divided into 6 zones in terms of the geological environment negative effect caused by groundwater exploitation. According to analysis, with the increasing intensity of human activities, geological environment issues become more and more serious, therefore it is vital to control the human activities within the scope of 5× 10~5 people/km~2 to 9.9× 10~5 people/km~2 for the effective control of the size of the affected area by geological environment problems.  相似文献   

内蒙古1979年五原6.0级和1996年包头6.4级地震的震源区构造   总被引：2，自引：2，他引：0       下载免费PDF全文

闻学泽 《地震地质》2014,36(3)

在内蒙古河套断陷带中—西段,1979年8月和1996年5月分别发生了五原6.0级地震和包头6.4级地震.针对这2次地震的发震构造,在前人研究工作的基础上,进一步集成活动构造、石油物探、重新定位的地震分布、烈度分布以及震源机制解等信息进行分析,构建通过这2次地震震源区的地震构造剖面,并重新确定了相应的发震断层.结果表明:1979年五原6.0级地震更可能是走向近EW、倾向S的色尔腾山山前主断层发生正断层作用的结果;而1996年包头6.4级地震更可能是乌拉山凸起之下的一条走向NWW、倾向SSW的无名隐伏断层发生斜滑正断层作用的结果.对这2次地震发震构造的新认识,能够最大程度符合并解释各自震源区的地表活动构造、余震分布、主震的烈度分布与震源机制解以及主震时的地面宏观破坏等现象.惟一不能完全解释的是包头地震的极震区(Ⅷ度区)面积约有2/5位于所判定的发震断层北侧(下盘).另外,包头地震发震构造的例子显示出在大型活动断陷带内部的相对凸起区之下,也可能存在具有发生强震能力的活动性正断层或斜滑正断层.  相似文献   

Acoustic-Power Maps of Solar Active Regions with Direction Filters and Phase-Velocity Filters     

Dean-Yi Chou  Zhi-Chao Liang  Ming-Hsu Yang  Ming-Tsung Sun 《Solar physics》2009,255(1):39-51

We study the properties of power maps of solar acoustic waves filtered with direction filters and phase-velocity filters. A direction filter is used to isolate acoustic waves propagating in a narrow range of directions. The acoustic-power map of the waves filtered with a direction filter shows extended reduced-power features behind magnetic regions with respect to the wave direction. A phase-velocity filter is further applied to isolate waves with similar wave paths. In the power maps of the waves filtered with both a direction filter and a phase-velocity filter, a reduced-power image of a sunspot appears behind the sunspot with respect to the wave direction. The distance between the sunspot and the secondary image is consistent with the one-skip travel distance of the wave packet associated with the phase-velocity filter. The waves filtered with direction and phase-velocity filters at the location of the secondary image could be used to probe the sunspot. In the quiet Sun, spatial fluctuations exist in any acoustic-power map. These fluctuations are mainly caused by interference among modes with the same frequency. The fluctuations are random with two properties: They change rapidly with time, and their magnitude decreases with the square root of the number of frames used in computing the acoustic-power map.  相似文献