月球重力场的确定及构建我国自主月球重力场模型的方案研究   总被引：3，自引：0，他引：3  

李斐  鄢建国 《武汉大学学报(信息科学版)》2007,32(1):6-10

对绕月卫星的运动规律以动力学方程的形式进行了描述，并讨论了绕月卫星定轨中动力法和几何法的适用性以及通过定轨观测获取月球重力场模型的计算方式和优化算法’在归纳月球重力场确定的技术流程的基础上。针对月球背面绕月卫星摄动无法观测的困难，分析了目前所能采取的各种处理办法及其特征。结合我国即将发射的“嫦娥卫星”装备有激光测高计这一特点，提出将月球表面地形与月球重力场之间的强相关性作为约束来确定我国自主重力场模型的设想。  相似文献   

执法为民依法治"震"     

陈俊晖  陈晓发 《国际地震动态》2007,(10):32-35

通过对防震减灾法在实施过程中存在不善于执法和执法不严等问题的分析,提出加强地震行政执法,依法保护全社会各行各业建设工程必须达到抗震设防要求,保证防震减灾工作有序地进行,切实收到减灾成效。笔者拟从端正执法思想,规范执法行为,强化执法监督三方面综述加强地震行政执法力度对防震减灾、造福民众的重要意义。  相似文献   

An Anisotropic Attenuation Law of Macroseismic Intensity Performed on Virtual Intensity Distribution of Seismogenic Zones     

Domenica Termini  Antonio Teramo  Carla Bottari  Tiziana Tuvè 《Pure and Applied Geophysics》2005,162(4):707-714

An anisotropic attenuation law, based on an anisotropic characterization of intensity distribution for seismogenic zones, is proposed. This approach, that distinguishes itself for its consistency to the observed data, initially reconfigured by filtering procedures, is particularly suitable for seismic hazard evaluation.  相似文献   

板块界面磁斥力形成与全球大型-超大型金矿分布规律初探   总被引：3，自引：3，他引：3       下载免费PDF全文

邓军  孙忠实  侯增谦  燕长海  李德胜  王庆飞  靳玄烨 《地质科学》2002,37(4):502-508

板块构造与全球大型-超大型金矿分布间的内在联系一直被世人所关注.本文根据板块体转动引起岩石剩磁矢量方向的变化(由原正-负磁极相对变为正-正极或负-负极相对)所产生的磁斥力以及磁斥力对金元素运移和富集的控制作用,探求磁斥力的形成特征与全球金矿分布规律的对应关系.基于磁力控矿理论基础、磁斥力形成和控矿机制及全球大型-超大型金矿分布规律的讨论,提出全球大型-超大型金矿床的形成,除有区域构造应力和重力等作用外,还应与磁斥力作用有关.磁斥力值、板块体旋转角度及金矿床的形成3者间具有一定的对应性,磁斥力大小与金矿床形成规模成正比.这种正比关系决定了全球大型-超大型金矿床空间展布主要呈环形、对顶角式和等距性分布,反映出全球成矿演化的总趋势.  相似文献   

永春地热资源赋存规律与开发研究     

陈文林 《中国煤田地质》2002,14(3):44-45,74

永春地热田热资源赋存规律是其特殊地质构造制约地下水运动的结果。温泉沿着北西向张性断裂和北东向压扭性断裂构造的复合部位出露，具有链状分布的特征。经对热田地质背景、水文地质条件及成因机理分析认为：地热水赋存在以北西向断裂上盘和北东向断裂构成的锐角楔形内，是理想的布井取水部位。  相似文献   

Material versus local incompressibility and its influence onglacial‐isostatic adjustment     

Zden&#;k Martinec  Malte Thoma  Detlef Wolf 《Geophysical Journal International》2001,144(1):136-156

We present an analytical form of the layer propagator matrix for the response of a locally incompressible, layered, linear‐viscoelastic sphere to an external load assuming that the initial density stratification ϱ ₀( r ) within each layer is parametrized by Darwin's law. From this, we show that the relaxation of a sphere consisting of locally incompressible layers is governed by a discrete set of viscous modes. The explicit dependence of the layer propagator matrix on the Laplace transform variable allows us to determine the amplitudes of the viscous modes analytically. Employing Darwin's parametrization, we construct three simplified earth models with different initial density gradients that are used to compare the effects of the local incompressibility constraint, div ( ϱ ₀ u )=0, and the material incompressibility constraint, div  u =0, on viscoelastic relaxation. We show that a locally incompressible earth model relaxes faster than a materially incompressible model. This is a consequence of the fact that the perturbations of the initial density are zero during viscoelastic relaxation of a locally incompressible medium, so that there are no internal buoyancy forces associated with the continuous radial density gradients, only the buoyancy forces generated by internal density discontinuities. On the other hand, slowly decaying internal buoyancy forces in a materially incompressible earth model cause it to reach the hydrostatic equilibrium after a considerably longer time than a locally incompressible model. It is important to note that the approximation of local incompressibility provides a solution for a compressible earth model that is superior to the conventional solutions for a compressible earth with homogeneous layers because it is based on an initial state that is consistent with the assumption of compressibility.  相似文献   

甘肃河东春旱的气候特征分析及预测模型   总被引：1，自引：1，他引：1  

郭江勇  李栋梁  崔风英  吴爱敏 《干旱气象》2001,19(1):5-8

利用河东 1968～ 1995年 55站的春季降水、气温资料 ,计算了春季干湿指数 ,划分了春旱标准 ,分析了其时空分布特征和变化规律 ,用REOF方法对旬降水量进行了分解 ,在气候分区的基础上 ,建立了河东春旱的均生函数预测模型  相似文献   

人工质量在砖混结构振动台试验中的作用   总被引：5，自引：0，他引：5  

黄维平  王连广 《地震工程与工程振动》2001,21(3):99-103

通过组合墙片的拟静力试验和模型房屋的振动台试验，分析研究了人工质量模拟对砖混结构振动台试验的作用和影响。研究表明，重力对结构的弯曲刚度有较大影响，但不影响结构的剪切刚度。在主拉应力破坏的条件下，结构的破坏荷载随重力的增加而增大。提出了不完全模拟的人工质量模型应满足的相似条件及如何根据模型试验结果估计原型结构的抗震能力。  相似文献   

地理信息系统的数据精度分析     

杜景龙  姜俐平 《测绘与空间地理信息》2001,24(1):27-28,48

数据是地理信息系统的重要组成部分 ,数据的精度对系统的功能影响很大。数据的误差主要来自四个方面 ,即数据源误差、数据输入误差、数据转换误差、分析误差 ,系统的总误差是上述各误差的累积。数据的误差必须与数据一起被纳入到系统当中加以分析 ,从而增加系统的可用性。  相似文献   

On the frequency distribution of turbidite thickness   总被引：1，自引：0，他引：1  

Peter J. Talling 《Sedimentology》2001,48(6):1297-1329

The frequency distribution of turbidite thickness records information on flow hydrodynamics, initial sediment volumes and source migration and is an important component of petroleum reservoir models. However, the nature of this thickness distribution is currently uncertain, with log‐normal or negative‐exponential frequency distributions and power‐law cumulative frequency distributions having been proposed by different authors. A detailed analysis of the Miocene Marnoso Arenacea Formation of the Italian Apennines shows that turbidite bed thickness and sand‐interval thickness within each bed have a frequency distribution comprising the sum of a series of log‐normal frequency distributions. These strata were deposited predominantly in a basin‐plain setting, and bed amalgamation is relatively rare. Beds or sand intervals truncated by erosion were excluded from this analysis. Each log‐normal frequency distribution characterizes bed or sand‐interval thickness for a given basal grain‐size or basal Bouma division. Measurements from the Silurian Aberystwyth Grits in Wales, the Cretaceous Great Valley Sequence in California and the Permian Karoo Basin in South Africa show that this conclusion holds for sequences of disparate age and variable location. The median thickness of these log‐normal distributions is positively correlated with basal grain‐size. The power‐law exponent relating the basal grain‐size and median thickness is different for turbidites with a basal A or B division and those with only C, D and E divisions. These two types of turbidite have been termed ‘thin bedded’ and ‘thick bedded’ by previous workers. A change in the power‐law exponent is proposed to be related to: (i) a transition from viscous to inertial settling of sediment grains; and (ii) hindered settling at high sediment concentrations. The bimodal thickness distribution of ‘thin‐bedded’ and ‘thick‐bedded’ turbidites noted by previous workers is explained as the result of a change in the power‐law exponent. This analysis supports the view that A and B divisions were deposited from high‐concentration flow components and that distinct grain‐size modes undergo different depositional processes. Summation of log‐normal frequency distributions for thin‐ and thick‐bedded turbidites produces a cumulative frequency distribution of thickness with a segmented power‐law trend. Thus, the occurrence of both log‐normal and segmented power‐law frequency distributions can be explained in a holistic fashion. Power‐law frequency distributions of turbidite thickness have previously been linked to power‐law distributions of earthquake magnitude or volumes of submarine slope failure. The log‐normal distribution for a given grain‐size class observed in this study suggests an alternative view, that turbidite thickness is determined by the multiplicative addition of several randomly distributed parameters, in addition to the settling velocity of the grain‐sizes present.  相似文献