以反应谱和功率谱密度函数表征的强震运动的统计特性   总被引：1，自引：0，他引：1  

江近仁  孙景江 《中国地震》1994,10(4):327-340

文中利用我国海城和唐山地震１９０条强震记录和美国西部１３８条强震记录研究了以反应谱和功率谱密度函数表征的强震运动的统计特性。反应谱用最大地面加速度归一化，即表为谱放大系数，功率谱密度函数用金井清谱描述。文中研究了参数的统计值和依赖性，以及谱放大系数和金井清谱参数与场地条件、震源和震中距等之间的相关性，分析比较了中美两国强震运动谱的统计特性，并对我国地震工程应用的强震运动谱的统计参数值的选取提出了建议。  相似文献   

华北地区重力场与沉积层构造   总被引：12，自引：2，他引：12  

冯锐  郑书真 《地球物理学报》1989,32(4):385-398

位于中朝准地台的华北地区是由几个不同的断块组成的,重力异常场的分布具有很强的浅部效应、块状分布和深浅叠加场的特点。重力的高程效应很复杂,不同波长的起伏变化有不同的影响系数。本文对布格改正的有关问题进行了讨论,指出华北如区表浅层的密度值偏低（2520kg/m³）,该区合理的布格改正公式为△g₂=-0.0879H。将重力场的垂直导数和向上延拓结合起来,有利于揭示地壳上部构造特征。本文搜集整理了由第四系到寒武系的沉积层资料,给出了沉积层总厚度和视密度的分布。对深部重力异常的分析表明,华北沉积层的形成有深源性质,在均衡调节中起着一定的内载荷作用。  相似文献   

Analysis of gravity anomalies over an inclined fault with quadratic density function   总被引：3，自引：0，他引：3  

D. Bhaskara Rao 《Pure and Applied Geophysics》1985,123(2):250-260

An attempt is made to interpret the gravity anomalies over an inclined fault with variable density contrast. The decrease of density contrast with depth in sedimentary rocks is approximated by a quadratic function. The anomaly equation of an inclined fault is derived with the quadratic density function. The constantsa ₀,a ₁ anda ₂ of the quadratic density function can be found from the known density-depth values. A synthetic anomaly profile of the fault model is interpreted by the non-linear optimisation technique using the Marquardt algorithm. The distances are measured from an arbitrary reference point and thus the origin of the fault model is also treated as an unknown parameter. For the assumed values of the constantsa ₀,a ₁ anda ₂, the various parameters of the fault model are found by the non-linear optimisation technique. The convergence of the method is shown by plotting the values of the objective function, lamda, and the parameters of the fault model with respect to iteration number. The two parameters inclination and origin are found to be correlated. The same program is used to interpret the gravity anomalies with different density contrasts. Finally, the use of modelling with the quadratic density function is discussed.  相似文献   

Exploratory spectral analysis of hydrological times series     

A. Ian McLeod  K. W. Hipel 《Stochastic Environmental Research and Risk Assessment (SERRA)》1995,9(3):171-205

Current methods of estimation of the univariate spectral density are reviewed and some improvements are made. It is suggested that spectral analysis may perhaps be best thought of as another exploratory data analysis (EDA) tool which complements, rather than competes with, the popular ARMA model building approach. A new diagnostic check for ARMA model adequacy based on the nonparametric spectral density is introduced. Additionally, two new algorithms for fast computation of the autoregressive spectral density function are presented. For improving interpretation of results, a new style of plotting the spectral density function is suggested. Exploratory spectral analyses of a number of hydrological time series are performed and some interesting periodicities are suggested for further investigation. The application of spectral analysis to determine the possible existence of long memory in natural time series is discussed with respect to long riverflow, treering and mud varve series. Moreover, a comparison of the estimated spectral densities suggests the ARMA models fitted previously to these datasets adequately describe the low frequency component. Finally, the software and data used in this paper are available by anonymous ftp from fisher.stats.uwo.ca.  相似文献   

NaCl—H_2O溶液包裹体的密度式和等容式及其应用   总被引：55，自引：1，他引：55  

刘斌  段光贤 《矿物学报》1987,(4)

由于含盐类包裹体不能应用现有的状态方程求解,作者根据实验数值,采用最小二乘法等,得到含盐度(wt%)≤25的NaCl-H_2O溶液包裹体的密度式和等容式。只要测定出包裹体的均一温度和含盐度,代入密度式,即可计算包裹体中的流体密度。再由此密度、含盐度的等容式,进一步可求得包裹体的形成温度和压力。最后,作者列举了三个实例。  相似文献   

Low frequency waves in plasmas with spatially varying electron temperature     

P. Guio  S. Børve  H. L. Pécseli  J. Trulsen 《Annales Geophysicae》2001,18(12):1613-1622

Low frequency electrostatic waves are studied in magnetized plasmas with an electron temperature which varies with position in a direction perpendicular to the magnetic field. For wave frequencies below the ion cyclotron frequency, the waves need not follow any definite dispersion relation. Instead a band of phase velocities is allowed, with a range of variation depending on the maximum and minimum values of the electron temperature. Simple model equations are obtained for the general case which can be solved to give the spatial variation of a harmonically time varying potential. A simple analytical model for the phenomenon is presented and the results are supported by numerical simulations carried out in a 2.5-dimensional particle-in-cell numerical simulation. We find that when the electron temperature is striated along B₀ and low frequency waves (_ci) are excited in this environment, then the intensity of these low frequency waves will be striated in a manner following the electron temperature striations. High frequency ion acoustic waves (_ci) will on the other hand have a spatially more uniform intensity distribution.  相似文献   

Triggered-lightning properties inferred from measured currents and very close electric fields   总被引：1，自引：0，他引：1  

V. Kodali  V.A. Rakov  M.A. Uman  K.J. Rambo  G.H. Schnetzer  J. Schoene  J. Jerauld 《Atmospheric Research》2005,76(1-4):355

Triggered-lightning properties, including dart-leader charge density, return-stroke propagation speed, dart-leader electric potential, dart-leader propagation speed, and dart-leader current, inferred from return-stroke current and very close electric field measurements, are presented. Although most of the estimates are based on relatively crude models, they are all generally in good agreement with independent measurements and/or theoretical considerations found in the literature. The results are likely to be applicable to subsequent strokes in natural lightning.  相似文献   

砂土的抗剪强度与干密度的曲线拟合     

龚平玲  邓飞 《矿产与地质》2005,19(2):207-208

利用曲线拟合的最小二乘法原理，确定砂土在某垂直压力下的抗剪强度与干密度的关系，并绘制曲线图，可避免人工处理数据的随意性，减小了误差。  相似文献   

堤防隐患探测实例分析   总被引：2，自引：0，他引：2  

石念增  刘康和 《地质灾害与环境保护》2005,16(4):376-382

在堤防隐患探测中，采用地质雷达、高密度电法、电测深法、地震折射波法等综合物探技术，并结合少量的土工试验资料，提高了物探成果的可靠性和实用性，取得了良好的应用效果．为堤防隐患探测提供了新的思路。  相似文献   

高密度电阻率法在东安金矿床勘探中的应用     

张海心  杨言辰 《吉林地质》2005,24(4):76-79

本文论述了高密度电阻率法在逊克县东安岩金矿床勘探中的应用效果;阐明了该方法在地质勘查中解决高阻脉状金矿体产状及埋深的技术手段.  相似文献