基于矢量波数变换法(VWTM)的多道Rayleigh波分析方法   总被引：4，自引：0，他引：4       下载免费PDF全文

杨振涛  陈晓非  潘磊  王建楠  徐剑侠  张大洲 《地球物理学报》2019,62(1):298-305

在近二十年来,多道面波分析法(MASW)由于其便捷、高效等特性在浅层地震勘探领域得到了广泛的应用.本文基于多道面波勘探的采集方式,提出了一种新的面波多道分析方法——矢量波数变换法(VWTM).该方法通过对震源的近似,基于水平层状模型得到台站与震源间近似格林函数,然后进行矢量波数变换得到含有高阶模态Rayleigh波(频率-相速度)频散能量图.本研究首先利用合成地震数据到频散能量图与理论频散曲线进行叠加分析该方法的有效性和正确性;然后与相移法进行对比分析,我们发现在频散能量图中VWTM法对基阶、高阶模态成像均具有更高的分辨率和成像质量;最后我们将其应用于实际多道瞬态面波探测中,通过与相移法进行对比分析,发现VWTM法是一种方便、实用、有效的Rayleigh波频散提取方法.VWTM法提取多模态的Rayleigh波频散特征具有巨大潜力,可为基阶、高阶面波频散联合反演提供丰富的高阶模态频散信息.  相似文献   

修正辛格式有限元法的地震波场模拟          下载免费PDF全文

苏波  李怀良  刘少林  杨顶辉 《地球物理学报》2019,62(4):1440-1452

三角网格有限元法具有网格剖分的灵活性,能有效模拟地震波在复杂介质中的传播.但传统有限元法用于地震波场模拟时计算效率较低,消耗较大计算资源.本文采用改进的核矩阵存储(IKMS)策略以提高有限元法的计算效率,该方法不用组合总体刚度矩阵,且相比于常规有限元法节省成倍的内存.对于时间离散,将有限元离散后的地震波运动方程变换至Hamilton体系,在显式二阶辛Runge-Kutta-Nystr9m(RKN)格式的基础之上加入额外空间离散算子构造修正辛差分格式,通过Taylor展开式得到具有四阶时间精度时间格式,且辛系数全为正数.本文从理论上分析了时空改进方法相比传统辛-有限元方法在频散压制、稳定性提升等方面的优势.数值算例进一步证实本方法具有内存消耗少、稳定性强和数值频散弱等优点.  相似文献   

Research and Application of In‐seam Seismic Survey Technology for Disaster‐causing Potential Geology Anomalous Body in Coal Seam     

TENG Jiwen  LI Songying  JIA Mingkui  LIAN Jie  LIU Honglei  LIU Guodong  WANG Wei  Volker SCH?PE  FENG Lei  YAO Xiaoshuai  WANG Kang  YAN Yafen  ZHANG Wanpeng 《《地质学报》英文版》2020,94(1):10-26

In order to effectively detect potential geology anomalous bodies in coal bearing formation, such as coal seam thickness variation, small faults, goafs and collapse columns, and provide scientific guidance for safe and efficient mining, the SUMMIT-II EX explosion-proof seismic slot wave instrument, produced by German DMT Company, was used to detect the underground channel wave with the help of transmission method, reflection method and transflective method. Region area detection experiment in mining face had been carried out thanks to the advantage of channel wave, such as its great dispersion, abundant geology information, strong anti-interference ability and long-distance detecting. The experimental results showed that: (1) Coal seam thickness variation in extremely unstable coal seam has been quantitatively interpreted with an accuracy of more than 80% generally; (2) The faults, goafs and collapse columns could be detected and predicted accurately; (3) Experimental detection of gas enrichment areas, stress concentration regions and water inrush risk zone has been collated; (4) A research system of disaster-causing geology anomalous body detection by in-seam seismic survey has been built, valuable and innovative achievements have been got. Series of innovation obtained for the first time in this study indicated that it was more effective to detect disaster-causing potential geology anomalies by in-seam seismic survey than by ground seismic survey. It had significant scientific value and application prospect under complex coal seam conditions.  相似文献   

Progress in the Researches of Fast Radio Bursts     

LI Long-biao  HUANG Yong-feng  GENG Jin-jun 《Chinese Astronomy and Astrophysics》2018,42(2):165-187

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Urbanization between compactness and dispersion: designing a spatial model for measuring 2D binary settlement landscape configurations     

Hannes Taubenböck  Michael Wurm  Christian Geiß  Stefan Dech  Stefan Siedentop 《International Journal of Digital Earth》2019,12(6):679-698

Measuring spatial patterns is a crucial task in spatial sciences. Multiple indicators have been developed to measure patterns in a quantitative manner. However, most comparative studies rely on relative comparisons, limiting their explanatory power to specific case studies. Motivated by advancements in earth observation providing unprecedented resolutions of settlement patterns, this paper suggests a measurement technique for spatial patterns to overcome the limits of relative comparisons. We design a model spanning a feature space based on two metrics – largest patch index and number of patches. The feature space is defined as ‘dispersion index’ and covers the entire spectrum of possible two-dimensional binary (settlement) patterns. The model configuration allows for an unambiguous ranking of each possible pattern with respect to spatial dispersion. As spatial resolutions of input data as well as selected areas of interest influence measurement results, we test dependencies within the model. Beyond, common other spatial metrics are selected for testing whether they allow unambiguous rankings. For scenarios, we apply the model to artificially generated patterns representing all possible configurations as well as to real-world settlement classifications differing in growth dynamics and patterns.  相似文献   

A Numerical Model for Nonlinear Wave Propagation on Non-uniform Current   总被引：3，自引：0，他引：3  

张洪生  王卫远  冯文静  杨建民  卢士强 《中国海洋工程》2010,24(1):15-28

On the basis of the new type Boussinesq equations (Madsen et al.,2002),a set of equations explicitly including the effects of currents on waves are derived.A numerical implementation of the present equations in one dimension is described.The numerical model is tested for wave propagation in a wave flume of uniform depth with current present.The present numerical results are compared with those of other researchers.It is validated that the present numerical model can reasonably reflect the nonlinear influences of currents on waves.Moreover,the effects of inputting different incident boundary conditions on the calculated results are studied.  相似文献   

Statistics from Lagrangian observations   总被引：1，自引：0，他引：1  

J.H. LaCasce 《Progress in Oceanography》2008,77(1):1-29

We review statistical analyses of Lagrangian data from the ocean. These can be grouped into studies involving single particles and those with pairs or groups of particles. Single particle studies are the most common. The prevalent analysis involves binning velocities geographically to estimate the Eulerian means and lateral diffusivities. However single particle statistics have also been used to study Rossby wave propagation, the influence of bottom topography and eddy heat fluxes. Other studies have used stochastic models to simulate dispersion, calculated Lagrangian frequency spectra and examined the relation between Lagrangian and Eulerian integral scales. Studies involving pairs of particles are fewer, and the results are not well-established yet. There are indications that pair separations grow exponentially in time below the deformation radius, as is also the case in the stratosphere. The behavior at larger scales is less clear, indicating either a turbulent cascade or dispersion by the sheared large-scale circulation. In addition, three or more particles can be used to measure relative vorticity and divergence.  相似文献   

Control effects of the synsedimentary faults on the basin-marginal fans in the central part of the deep-water area of early Oligocene Qiongdongnan Basin,South China Sea     

Guangzeng Song  Zengxue Li  Haizhang Yang  Dongdong Wang  Ying Chen  Rui Sun 《海洋学报(英文版)》2021,40(2):54-64

The synsedimentary faults and basin-marginal fans located in the central part of the deep-water area of the early Oligocene Qiongdongnan Basin have been investigated using seismic profiles, boreholes, and well-log data.Through the formations of the characterized paleogeomorphology, such as transverse anticlines, fault ditches,and step-fault belts, the synsedimentary faults are known to have controlled the development position,distribution direction, and extension scales of the basin-marginal fans. For example, at the pitching ends of two adjacent faults, transverse anticlines developed, which controlled the development positions and distributions of the fans. During the early Oligocene, the faults controlled the subsidence center, and fault ditches were formed at the roots of the faults. In the surrounding salient or low salient areas, which were exposed as provenance areas during early Oligocene, the fault ditches acted as the source channels and determined the flow paths of the clastics, where incised valley fills were obviously developed. The fault ditches which developed in the sedimentary basins were able to capture the drainage systems and influenced the distributions of the fans. The large boundary faults and the secondary faults generated two fault terraces and formed step-fault belts. The first fault terrace caused the clastics to be unloaded. As a result, fans were formed at the entrance to the basin. Then, the second fault terrace caused the fans to move forward, with the fans developing in a larger extension scale. The results obtained in this study will potentially be beneficial in the future prospecting activities for reservoirs and coalmeasure source rocks in the basins located in the deep-water areas of the South China Sea.  相似文献   

Analytical study of the effect of the geometrical parameters during the interaction of regular wave-horizontal plate-current     

NAASSE Smail  ERRIFAIY Meriem  CHAHINE Chakib 《海洋学报(英文版)》2019,38(5):10-20

The present work is an analytical study of the influence of geometrical parameters, such as length, thickness and immersion of the plate, on the reflection coefficient of a regular wave for an immersed horizontal plate in the presence of a uniform current with the same direction as the propagation of the incident regular wave. This study was performed using the linearized potential theory with the evanescent modes while searching for complex roots to the dispersion equation that are neither pure real nor pure imaginary. The results show that the effects of the immersion and the relative length on the reflection coefficient of the plate are accentuated by the presence of the current, whereas the plate thickness practically does not have an effect if it is relatively small.  相似文献   

盛行风条件下横向沙丘群丘间走廊中次生气流的研究初报     

韩广  尤莉  丁占良 《中国沙漠》2019,39(5):21-28

按照经典风沙物理学理论,横向沙丘下风侧由于气流分离会产生横轴涡旋,然而我们多年来在科尔沁沙地多处开展的沙丘群考察和观测中,经常观察到西北风天气条件下丘间走廊里发育着稳定的南向和西南向气流。为了解这种次生气流的基本特征,我们选择科尔沁沙地西部一片典型横向沙丘群,利用自动气象站进行了风季强风天气的风力观测。结果表明：（1）这种次生气流比较稳定,冬季基本以南风为主,春季以西南风为主;（2）风速会大幅度降低,幅度30%~50%;（3）冬季湍流强度明显小于春季,表明不同季节的局地大气层结状况影响丘间走廊的次生气流;（4）冬季的次生气流主要加深走廊底部,协助沙丘前移,而在春季除了加深走廊外,还促进了走廊的拓宽。  相似文献