跟踪法机助采样快速精密陀螺定向系统     

蒋理兴  于来法 《测绘学报》1992,21(2):134-143

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S_q发电机电流的逐日变化和S_q指数   总被引：4，自引：5，他引：4       下载免费PDF全文

徐文耀 《地球物理学报》1992,(6)

用中国地磁台站的资料,研究了S_q逐日变化的形态学特征,用理论模型计算了磁层环电流、部分环电流、场向电流、磁尾电流、Chapman-Ferraro电流的地磁效应.在消除了这些磁层电流体系的影响之后,得到了电离层潮汐风发电机电流产生的磁场S_q变化.对1973年的资料研究表明,S_q发电机电流的逐日变化主要表现在强度上,即使在磁扰期间,也可以分离出形态稳定的S_q变化.由此提出了一种新的地磁指数——S_q指数,用来描述S_q发电机电流强度的逐日变化.  相似文献   

Pore fluid pressure effects in anisotropic rocks: Mechanisms of induced seismicity and weak faults     

Qiang Chen  Amos Nur 《Pure and Applied Geophysics》1992,139(3-4):463-479

Many observations and studies indicate that pore fluid pressure in the crustal rocks plays an important role in deformation, faulting, and earthquake processes. Conventional models of pore pressure effects often assume isotropic porous rocks and yield the nondeviatoric pressure effects which seem insufficient to explain diverse phenomena related to pore pressure variation, such as fluid-extraction induced seismicity and crustal weak faults. We derive the anisotropic effective stress law especially for transversely-isotropic and orthotropic rocks, and propose that the deviatoric effects of pore fluid pressure in anisotropic rocks not only affect rock effective strength but also cause variation of shear stresses. Such shear stress variations induced by either pore pressure buildup or pore pressure decline may lead to faulting instability and trigger earthquakes, and provide mechanisms for the failure of crustal weak faults with low level of shear stresses. We believe that the deviatoric effects of pore fluid pressure in anisotropic rocks are of wide application in studies of earthquake precursors and aftershocks, oil and gas reservoir characterization, enhanced oil recovery, and hydraulic fracturing.  相似文献   

辽东湾丛式钻井陀螺侧钻及导向钻井防碰技术     

姜伟 《四川地质学报》1992,(4)

本文介绍渤海辽东湾实验区AI平台丛式定向井最后钻完的3口侧钻绕障井。在有邻井和本井套管磁干扰情况下,特别是与邻井间距最小仅为0.6m,采用陀螺定向侧钻以及导向钻井技术相结合,安全顺利的钻完了这3口井。总结和介绍了侧钻、防碰的工艺特声,以及安全措施。研究和分析了使用陀螺定向侧钻,钻速与造斜率,井眼轨迹合理控制等问题。  相似文献   

中低纬过渡地区潜热影响下中尺度扰动的对称发展          下载免费PDF全文

吴勇  欧阳首承 《大气科学》1995,19(5):631-635

本文引入第二科里奥利参数讨论了中低纬过渡地区含非绝热(潜热)作用的对称扰动波包发展问题。结果表明:这一地区扰动波包的发展不仅包含了中高纬度波包发展条件［1］，而且与潜热和基本风场梯度经向切变及波包传播的非垂直性有关。过渡地区基本风场的作用是通过第一和第二科里奥利参数完成的。  相似文献   

四川盆地区域化探扫面工作方法初步研究     

何真毅 《四川地质学报》1995,(2)

四川盆地可分为川东平行岭谷区、盆周低山丘陵区、川中丘陵区、川西平原区。论述了各区的采样对象及采样点密度。川东平行岭谷区及盆周低山区的化探成果对寻找非金属矿产及某些金属矿产效果显著。川中典型区土壤地球化学资料，能为农业、环境等多目标服务，对农业区划、科学施肥、合理种植、土壤改良等提供了重要的地球化学依据。证实了川西平原油气化探方法的有效性。  相似文献   

用地震活动性指数A（b）等资料判断图像以后有无主震及震级大小     

黄存楚  陈忠奇 《地震地磁观测与研究》1993,14(2):35-41

用 A(b)指数判断图象以后有无主震,其效果颇好。A(b)指数能将有主震 M_L≥5.0与有主震 M_L≤4.7(或无主震)区别开来。再加地震活动的范围、强度资料的配合,能判断主震的大小。此方法的资料自检准确率陆地达96%,震例检验的准确率也高。这样的判断,对用图象作地震预报有重要的作用。  相似文献   

Study on terrestiral noise in data of geomagnetic total field in North China     

Xi-Xian Ren  Yu-Min Zhang  Zhi-Jia Zhan  Jin-Tian Gao 《地震学报(英文版)》1993,6(4):939-947

The terrestrial noise in the differencial data of geomagnetic total field recorded at 21h in North China was fitted by using the geomagnetic vector data from Beijing Observatory. The terrestrial noise level and its spatial feature in this region was discussed. A method, which may be useful for justifying the quality of fitting, was provided in this paper. The analysis indicates that the terrestrial noise is one of the important noise in tectonomagnetic study. It is shown that the susceptibility effect is quite small and the orientation effect is the main component in the terrestrial noise in North China. The rough spatial feature of the magnetic anomaly in crustal substance was infered from the spatial feature of terrestrial noise. The measurement precision and the source noise level of data at 21h in this region were obtained in the analysis of residual noise. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 441–447, 1993.  相似文献   

Determining short-term changes in the hydraulic properties of a sandy-loam soil by a three-run infiltration experiment     

V. Bagarello  N. Cecere  S. M. David 《水文科学杂志》2020,65(7):1191-1203

ABSTRACT

Soil structure-dependent parameters can vary rapidly as a consequence of perturbing events such as intense rainfall. Investigating their short-term changes is therefore essential to understand the general behaviour of a porous medium. The aim of this study is to gain insight into the effects of wetting, perturbation and recovery processes through different sequences of Beerkan infiltration experiments performed on a sandy-loam soil. Two different three-run infiltration experiments (LHL and LLL) were carried out by pouring water at low (L, non-perturbing) and high (H, perturbing) heights above the soil surface and at short time intervals (hours, days). The results demonstrate that the proposed method allows one to capture short-term variations in soil structure-dependent parameters. The developed methodology is expected to simplify the parameterization of hydrological models with temporally variable soil hydraulic properties.  相似文献   

Influence of forest fire episodes on the distribution of gaseous air pollutants over Uttarakhand,India     

Yesobu Yarragunta  Debashis Mitra  Harish Chandra Chandola 《地理信息系统科学与遥感》2020,57(2):190-206

ABSTRACT

Widespread forest fire events occurred in the foothills of North Western Himalaya during 24 April to 2 May 2016 (Event-1) and 20–30 May 2018 (Event-2). Their impacts were investigated on the distribution of pollutant gases ozone (O₃), carbon monoxide (CO), and oxides of nitrogen (NOx) over Uttarakhand using simulations of Weather Research and Forecasting model coupled with chemistry (WRF-Chem) and in-situ observations of these gases over Dehradun, the capital of Uttarakhand. During Event-1, the observed CO mixing ratio over Dehradun increased from 25 April 2016 onwards, attained maximum (705.8 ± 258 ppbv) on 2 May 2016 and subsequently decreased. The rate of increase of daily baseline CO was 29 ppbv/day during HFAP (High Fire Activity Period). During Event-2, daily average concentrations of CO, O₃, and NOx showed systematic increase over Dehradun during HFAP period. The rate of increase of CO was 9 ppbv/day, while it was very small for NOx and O₃. To quantitatively estimate the influence of forest fire emissions, two WRF-Chem simulations were made: one with biomass burning (BB) emissions and other without BB emissions. These simulations showed 52% (34%) enhancement in CO, 52% (32%) enhancement in NOx, and 11% (9%) enhancement in O₃ during HFAP for Event-1 (Event-2). A clear positive correlation (r = 0.89 for Event-1, r = 0.69 for Event-2) was found between ?O₃ (O_{3with BB} minus O_{3without BB}) and ?CO (CO_{with BB} minus CO_{without BB}), indicating rapid production of ozone in the fire plumes. For both the events, the vertical distribution of ?O₃, ?CO, and ?NOx showed that forest fire emissions influenced the air quality upto 6.5 km altitude. Peaks in ?O₃, ?CO, and ?NOx during different days suggested the role of varying dispersion and horizontal mixing of fire plumes.  相似文献