VLBI and VLA observations of intraday polarization variability in 0917+624 and 0954+658     

D. C. Gabuzda  P. YU. Kochenov  R. I. Kollgaard  T. V. Cawthorne 《Monthly notices of the Royal Astronomical Society》2000,315(2):229-240

Total intensity and polarization λ =6 cm Very Large Array (VLA) and global very long baseline interferometry (VLBI) images of the quasar 0917+624 and the BL Lacertae object 0954+658 (both at epoch 1991.43) are analysed. Integrated measurements using the VLA during the VLBI observations indicated that, although there were no substantial total intensity variations, there were significant polarization variations for both sources during the 24-h VLBI experiment. The VLBI data were divided into 2–3 h segments in order to try to identify corresponding rapid variability in the VLBI structure. This analysis revealed intraday variability (IDV) in the VLBI core of 0917+624: both the polarized flux and the polarization position angle varied substantially on time-scales of ∼5–10 h. There is evidence that the VLA polarization variations for 0954+658 occurred in an inner VLBI jet component, where the polarized flux varied by ∼30–40 per cent on time-scales of ∼2 h. 0917+624 and 0954+658 were observed together with 0716+714, an object that also displayed IDV in the polarized flux density measured during our experiment (analysed in a separate paper). These three sources were targeted for the VLBI observations since they had been previously identified as intraday variables, but we had no way of knowing whether they would vary during our observations. The fact that all three exhibited IDV in polarization (but not in total intensity) during our experiment suggests that polarization IDV occurs frequently in at least some IDV sources.  相似文献   

珠江口盆地白云凹陷东沙25凸起构造演化     

张翠梅  赵中贤  孙珍  庞雄  柳保军  李鹏春 《吉林大学学报(地球科学版)》2013,43(1):57-66

隆起带的形成和演化分析对于油气勘探具有重要的指导意义。通过对比生长地层法、沉降史回剥技术和剩余构造沉降3种构造演化的手段,旨在全面揭示东沙（DS）25凸起的演化历史。依据生长地层的厚度、地层反射终端等特征划分出白云凹陷DS25凸起演化的主要阶段;运用回剥法恢复DS25凸起的沉降历史和与周缘地区的沉降差异;结合剩余构造沉降分析,定量判断隆起的抬升、沉降和差异沉降作用及发育时期。在对以上3种方法对比综合的基础上,综合生长地层指示的重要构造变革界面、沉降史恢复和剩余构造沉降精细划分的沉降阶段和构造运动形式,重建DS25凸起演化过程,并提出以下5个演化阶段：65～30 Ma,凸起顶部遭受强烈剥蚀;30 Ma左右,凸起发生大规模抬升;30～23.8 Ma,发生微弱沉降;23.8～10.5 Ma,发生差异沉降,并出现三幕强烈沉降;10.5 Ma至今,凸起经历持续抬升。  相似文献   

渤中25-1低渗透油田地应力分布特征及对开发的影响   总被引：2，自引：2，他引：0  

廖新武  刘奇  李超  祖克威  周军良  黄凯 《地质力学学报》2015,21(1):30-37

利用有限元方法, 对渤中25-1低渗透油田现今地应力状态进行数值模拟研究, 并结合低渗透储层地质特征, 分析地应力对油田开发的影响。数值模拟结果表明, 渤中25-1低渗透油田沙二和沙三段的现今地应力为压应力, 以北东东—南西西向为水平最大主应力的主要优势方位, 地应力在平面上受断层、构造起伏和沉积微相控制明显。根据地应力状态, 分析研究区的人工压裂裂缝为垂直裂缝。在远离断层的断块中部, 人工压裂缝的展布方向主要为北东东—南西西方向; 在断层附近, 由于水平最大主应力方向发生偏转, 人工压裂缝的延伸方向也会发生一定偏转, 部署开发井网时需要根据断层附近地应力的实际分布规律进行相应调整。   相似文献   

塔里木盆地北部塔河油田原油分子地球化学特征及成因类型划分   总被引：4，自引：1，他引：3  

王传刚  王铁冠  张卫彪  何发歧 《沉积学报》2006,24(6):901-909

GC、GC-MS、GC-MS-MS分析表明,塔河17区块各油藏原油饱和烃、芳烃生物标志物组成和稳定碳同位素特征具有同源性,即塔河原油来自相同的烃源灶（或烃源层）。然而,对原油物性特征、成熟度特征、生物降解特征及原油馏分碳同位素组成等的深入研究发现,塔河原油属于早、晚两次充注成藏:早期充注为一般成熟型原油,相当于Ro值0.70%0.80%成熟阶段的生排烃产物,遭受生物降解后具有重、稠油特征,主要分布在4、6、7区下奥陶统储层中;晚期成藏原油相当于Ro值0.80%1.00%的高成熟阶段的生烃产物,表现为正常油、甚至轻质油或凝析油,在塔河油田广泛分布,并可以与早期充注油藏原油的生物降解残留成分进行充分混合,呈现复杂的地球化学特征。   相似文献   

与遥感发展同行——纪念《遥感学报》更名25周年     

童庆禧 《遥感学报》2021,25(1):1-14

《环境遥感》杂志更名为《遥感学报》已有25个年头,25年来中国经济社会发生了根本性的变化,中国的遥感科技也经历了从弱到强的转变过程.《遥感学报》正是这一变革的参与者、见证者和同行者.本文首先论述了自《遥感学报》更名后国内外遥感科技发展的历史背景以及国际遥感科技发展方向性的重大改变,全球变化已成为遥感的重大研究课题.文中...  相似文献