A Linear Dependence between the Magnitude and the Logarithm of the Length of the Time the Quasars OJ287 and 3C345 Stay below this Magnitude     

Jin He  G.Z. Xie 《Astrophysics and Space Science》1997,254(2):223-232

We have studied the optical historical light curves of two Active Galactic Nuclei (AGNs): OJ287 and 3C345. We find a linear dependence between the magnitude and the logarithm of the length of the time the objects stay below this magnitude. The relation may originate from a fractal structure of the light curve. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Cosmological implications of BL Lac objects     

G. Z. Xie  F. K. Liu  Y. Y. Zhu  J. H. Fan  R. W. Lu 《Astrophysics and Space Science》1991,179(2):321-329

It has become clear in recent years that relativistic beaming is a good explanation for the BL Lac phenomenon. Of studies based on the relativistic beaming model of BL Lac objects, we note that the orientation of jet's axis to the line-of-sight is very small and, therefore, the observed flux emitted from a rapidly moving source is orders of magnitude higher than the flux in its rest-frame:F _obs = ^{3 +} F _intr, where is the bulk relativistic Doppler factor. Then the observed apparent magnitudem _v must be corrected for this effect. For our 39 samples, the corrected apparent magnitudem _v ^corr and logZ have a good correlation.  相似文献   

The investigation of the solar wind transsonic region at meter wavelengths     

N. A. Lotova  Ya. V. Nagelys 《Solar physics》1988,117(2):407-414

Radio astronomy experiments designed to probe the interplanetary plasma close to the Sun have been carried out at the wavelength = 2.92 m using the occultation method. The experiments are based on a modification of the occultation method by which the sources, in this case quasars, are used to measure the radial dependence of the apparent source size, the scattering angle (R). The radial dependence of this source size (R) reveals that an anomalous enhancement in the scattering appears at radial distances from about 16 to 30 R , which is associated with the solar wind transsonic region. It is shown by analysis of the theoretical equations that the radial profiles of both the source size (R) and the scintillation index m(R) are consistent in the near solar interplanetary medium (R 40 R ). Combining these two independent applications of the occultation method extends the range of the investigation and provides a powerful new diagnostic of the solar wind transsonic region.  相似文献   

Impact of land use covers upon karst processes in a typical Fengcong depression system of Nongla, Guangxi, China   总被引：2，自引：0，他引：2  

Cheng Zhang  Jianguo Pei  Yunqiu Xie  Jianhua Cao  Lanling Wang 《Environmental Geology》2008,55(8):1621-1626

The direction and intensity of karst processes can be deeply affected by soil physical and chemical variations which were resulted from land use. Taking Nongla Fengcong depression area, Mashan County, Guangxi as an example, authors discussed the impact of land use on karst processes based on the data of field limestone tablet. The results showed that the corrosional rates at varied soil depth are quite different. Corrosional rate in woodland and orchard is mostly bigger than 20 mg/a, which is much higher than that in tilled land and shrub. Generally, corrosional rate decreased from orchard, woodland, tilled land, fallow land and shrub successively, in which soil organic matter (OM) and soil pH are two major controlling factors: corrosion process is controlled remarkably by soil OM in woodland and orchard. The higher the organic matter content is and the less the pH value is, the higher the corrosional rate is. Owing to lower organic matter content, the corrosional rate is mainly affected by soil CO₂ in tilled land and shrub.  相似文献   

The Ruiga intrusion: A typical example of a shallow-facies paleoproterozoic peridotite-gabbro-komatiite-basaltic association of the Vetreny Belt,Southeastern Fennoscandia     

V. S. Kulikov  Ya. V. Bychkova  V. V. Kulikova  Yu. A. Kostitsyn  O. S. Pokrovsky  M. V. Vasil’ev 《Petrology》2008,16(6):531-551

The Ruiga differentiated mafic-ultramafic intrusion in the northwestern part of the Vetreny Belt paleorift was described for the first time based on geological, petrological, geochronological, and geochemical data. The massif (20 km² in exposed area) is a typical example of shallow-facies peridotite-gabbro-komatiite-basalt associations and consists of three zones up to 810 m in total thickness (from bottom to top): melanogab-bronorite, peridotite, and gabbro. In spite of pervasive greenschist metamorphism, the rocks contain locally preserved primary minerals: olivine (Fo _75–86), bronzite, augite of variable composition, labradorite, and Cr-spinels. A mineral Sm-Nd isochron on olivine melanogabbronorite from the Ruiga Massif defines an age of 2.39 ± 0.05 Ga, while komatiitic basalts of the Vetreny Belt Formation were dated at 2.40–2.41 Ga (Puchtel et al., 1997). The rocks of the Ruiga intrusion and lava flows of Mt. Golets have similar major, rare-earth, and trace element composition, which suggests their derivation from a single deep-seated source. Their parent magma was presumably a high-Mg komatiitic basalt. In transitional crustal chambers, its composition was modified by olivine-controlled fractionation and crustal contamination, with the most contaminated first portions of the ejected melt. In terms of geology and geochemistry, the considered magmatic rocks of the Vetreny Belt are comparable with the Raglan Ni-PGE komatiite gabbro-peridotite complex in Canada (Naldrett, 2003).  相似文献   

南海西部海域新生代构造古地理演化及其对油气勘探的意义   总被引：6，自引：2，他引：4       下载免费PDF全文

谢锦龙  黄冲  向峰云 《地质科学》2008,43(1):133-153

南海西部海域构造复杂,主要发育有北东—北东东向、北西向和近南北向3组深大断裂。其中,北西向断裂与板块汇聚、碰撞有关,多具走滑性质;北东—北东东向断裂具有与中国东部裂谷盆地相似的发育特点,呈张扭性质;近南北向断裂可能是南海在扩张活动期间于洋、陆壳过渡部位形成的走滑调节断裂,是洋盆扩张的西部边界。新生代里,南海经历了4次成盆事件与3期扩张活动,盆地经历了古新世—中始新世陆缘断陷、渐新世—早中新世扩展与中中新世以来的热沉降3个演化阶段。陆缘断陷阶段的充填系列主要是北东—北东东向与北西向的河流—冲积扇、湖泊沼泽等陆相沉积及火山岩等;盆地扩展阶段表现为中-小型断陷、断-坳陷逐渐复合与联合为大-中型坳陷,古地理格局逐渐由河流与湖沼陆相环境演变为滨海至浅海相的沉积环境;热沉降阶段的成盆活动逐渐减弱以至停止,地层表现超覆,盆地出现联合迹象。结合以往勘探与油气资源调查成果分析,认为南海西部海域陆架陆坡区发育的大-中型沉积盆地石油地质条件良好,蕴藏着丰富的油气资源,勘探潜力巨大。  相似文献   

华南前寒武系基底变质杂岩和中-新生代地幔岩的稀有气体同位素组成及其大地构造意义          下载免费PDF全文

谢窦克  邢光福  陆志刚  陈荣  周宇章 《地质科学》2008,43(1):175-204

对华南前寒武系变质岩浆杂岩稀有气体He、Ne、Ar和Xe的系统研究表明:扬子克拉通基底为含高³He的下地壳"原始岩石层",(³He/⁴He)×10^-6比值为2.8～4.6;而华夏板块基底变质岩浆杂岩则是在缺乏³He、低(³He/⁴He)×10^-8比值(3.15～17.7)的构造环境下形成的大陆中-上地壳变质岩浆杂岩层,反映出两者基底性质迥然不同。华南中-新生代爆破岩筒He同位素组成相反,相对稳定的扬子克拉通(³He/⁴He)×10^-8比值仅0.18～4.22,而郯庐-四会-吴川断裂以东,中-新生代活动地块(太平洋构造域)(³He/⁴He)×10^-8比值高达3.7～20.5。He同位素表明郯庐-四会-吴川断裂带为切割深至地幔的边界深大断裂,是扬子克拉通与华夏板块间的边界且控制了燕山期火山-侵入岩浆向西扩展。Ar同位素组成表明华南大陆中-新生代地幔形成接近"均一"的地幔组份。¹³⁶Xe/¹³⁰Xe-¹²⁹Xe/¹³⁰Xe相关组份表明它们具有地幔柱岩石同位素组成特征。  相似文献   

三维抛物方程Douglas交替方向隐格式的稳定性和收敛性     

李弓春  谢树森 《中国海洋大学学报(自然科学版)》2001,31(4):626-632

作者研究三维变系数抛物方程 Douglas交替方向隐格式的稳定性和收敛性。采用 H1能量估计方法 ,证明格式按离散 H1范数是绝对稳定的 ,并且收敛阶为 O(Δ t2 + h2 )  相似文献   

庵东浅滩沉积分带和沉积速率   总被引：4，自引：0，他引：4  

李炎  谢钦春 《海洋学研究》1993,11(1):21-33

杭州湾南岸的庵东浅滩具有地貌特征、沉积类型和沉积构造各异的三个沉积相带。垂向沉积带为潮滩沉积体的盖层,以泥滩、粘土质粉砂和薄砂泥交互层为特征;改造带位于中低潮位线附近,以粉砂滩、潮沟系统、粉砂沉积和沙波层理为特征;横向沉积带为潮滩堆积体的基础,以滩坡、粉砂及细砂质粉砂沉积、冲刷-充填构造为特征。据潮汐韵律层的统计,庵东浅滩沉积速率的短周期分量,常态条件下为每半日潮周期0.1～2.0cm,异常条件下可达每半日潮周期4～64cm。沉积速率的长周期分量,据地形对比和~(210)Pb推算,垂向沉积带为2～4.5cm/a;改造带中的粉砂滩为2.1～4.5cm/a,潮沟影响范围内为1～10~1cm/a量级;横向沉积带则以高于50cm/a的高沉积速率和变幅为主。近10年来,该浅滩的年淤积量为6×10~7t/a,其中85％集中于横向沉积带。  相似文献   

Characteristics of Scour and Deposition in Front of Breakwaters Under Irregular Broken Clapotis   总被引：1，自引：0，他引：1  

高学平张亚  李昌良 《中国海洋工程》2004,18(3):493-500

First the scour and deposition patterns of the sandy seabed in front of a vertical breakwater under the action of irregular broken clapotis are investigated experimentally and classified into five types: scour type Ⅰ , scour type Ⅱ, scour type Ⅲ, deposition type Ⅰ, and deposition type Ⅱ . Secondly, the processes of formation of scour and deposition patterns are probed in comparison with those induced by regular broken clapotis and standing waves. Thirdly, the criteria for distinguishing scour and deposition patterns under irregular broken clapotis are presented.  相似文献