Experimental investigation of the elastic modulus of a fractal system—A model of fractured rocks     

T. L. Chelidze  H. Spetzler  I. C. Getting  Z. A. Avaliani 《Pure and Applied Geophysics》1990,134(1):31-43

The elastic properties of a physical model representing a damaged rock matrix were studied using a square lattice deformed under tensile stress. The elastic modulusM of such a system varies in agreement with percolation theory as|x–x _c | ^f , wherex is the damage parameter andx _c the threshold value of the damage parameter,f3.6. Atxx _c the scale dependence ofM can be expressed asML ^–f/v , whereL is the size of the sample andv the correlation exponent in percolation theory.The experimental results are of interest in assessing elastic properties in earthquake focal zones and fault zones in general.  相似文献   

预测陕西关中地区需水量的改进GM(1,1)模型   总被引：6，自引：0，他引：6  

王菊翠  曹明明  仵彦卿 《干旱区地理》2006,29(1):35-41

需水量评价与预测是水资源规划与管理一项重要的研究内容。本文采用定额法计算需水量。通过对陕西关中地区需水量要素组成的分析,认为需水量要素属平稳时间序列,且一阶累加生成数据系列满足指数规律,符合灰色预测条件。为了提高GM(1,1)模型的精度,采用一种改变背景值的新方法,即:中心逼近方法。通过精度检验,中心逼近式GM(1,1)模型平均误差百分比、误差平方和分别比传统的GM(1,1)模型提高了0.147和1.579。用中心逼近式GM(1,1)模型预测需水量各要素近期和中长期值,经检验,其中非农业人口、农业人口、耕地面积、工业总产值预测模型满足一级模型,等级为良好。牲畜头数预测模型为不合格模型,分析其原因,主要是因为时间序列数据不完全符合指数规律。通过定额法计算,预计75%保证率时2005年和2010年关中地区工农业需水量分别占总需水量的92.21%和89.75%,生活需水量分别占7%和9.04%。  相似文献   

库姆塔格沙漠"羽毛状沙丘"形态的示量特征   总被引：10，自引：2，他引：10  

刘虎俊  王继和  廖空太  郑庆中  张锦春  丁峰  唐进年  俄有浩  苏志珠  翟新伟  张国忠 《干旱区地理》2006,29(3):314-320

通过卫星照片判读和实地观测,库姆塔格沙漠的“羽毛状沙丘”由两种风沙地貌构成：东北-西南走向的新月形“沙垄”为“羽轴”；垄间分布的波状微起伏的“大沙波”为“羽枝”,“大沙波”与沙垄的夹角为75°～103°。二者组合成类似“羽毛”的风沙地貌。新月形“沙垄”由单个新月形沙丘的前一沙丘的迎风坡与后一沙丘东翼相连构成“沙垄”。组成“沙垄”的新月形沙丘的两翼平均长37．5m,翼间距30～66m,沙丘高3～19m；在所观测区域内,沙丘沙的分选性由南向北变差。新月形“沙垄”长为3～22km,垄间距为1～3km,其问分布浅色和暗色相间的波状微地貌,暗色部分平均宽24．3m,浅色部分的平均宽11．6m。暗色部分表层沙粒的粒径有60%在1．00～0．25mm之间,以暗色矿物为主,而浅色部分表层沙粒的粒径的90%在1．00～0．25mm之间,分选性相对暗色部分较好,以石英等浅色矿物为主。暗色和浅色微地貌成对出现,相对高差约7cm。这种波状微地貌在库姆塔格沙漠中北部重复出现,类似于风沙地貌分类的沙波,暂称其为“大沙波”。  相似文献   

Mais comment s'écoule donc un glacier ? Aperçu historique     

Frédérique Rémy  Laurent Testut 《Comptes Rendus Geoscience》2006,338(5):368-385

Ice and snow have often helped physicists understand the world. On the contrary it has taken them a very long time to understand the flow of the glaciers. Naturalists only began to take an interest in glaciers at the beginning of the 19th century during the last phase of glacier advances. When the glacier flow from the upslope direction became obvious, it was then necessary to understand how it flowed. It was only in 1840, the year of the Antarctica ice sheet discovery by Dumont d'Urville, that two books laid the basis for the future field of glaciology: one by Agassiz on the ice age and glaciers, the other one by canon Rendu on glacier theory. During the 19th century, ice flow theories, adopted by most of the leading scientists, were based on melting/refreezing processes. Even though the word ‘fluid’ was first used in 1773 to describe ice, more the 130 years would have to go by before the laws of fluid mechanics were applied to ice. Even now, the parameter of Glen's law, which is used by glaciologists to model ice deformation, can take a very wide range of values, so that no unique ice flow law has yet been defined. To cite this article: F. Rémy, L. Testut, C. R. Geoscience 338 (2006).  相似文献   

爆破夯实技术在水下地基处理中的应用          下载免费PDF全文

张维正 《探矿工程》2006,33(10):60-62

以某杂货码头和集装箱重力式码头水下地基处理工程为例，介绍了其地基处理的爆夯试验过程，得出了一次性爆破夯实厚层块石抛石基床的爆夯参数，并对其施工过程进行了监测。总结了类似工程施工的经验与教训。  相似文献   

Correct nomenclature for the Angadimogar pluton, Kerala, southwestern India     

H. M. Rajesh 《Journal of Earth System Science》2006,115(2):239-248

The proper usage of modal composition and geochemical classification of granitoids is discussed for assigning a proper nomenclature for the Angadimogar pluton, Kerala, southwestern India. This discussion is mainly aimed at addressing questions concerning the nomenclature of Angadimogar pluton (syenitevs. granite). Modal composition and whole-rock XRD data clearly show that the pluton exposed near Angadimogar is a quartz-syenite and its geochemistry is typical of a ferroan, metaluminous, alkali (A-type) granitoid  相似文献   

Assessing the Vibrational Frequencies of the Cathedral of Cologne (Germany) by Means of Ambient Seismic Noise Analysis   总被引：1，自引：0，他引：1  

Andreas Fäcke  Stefano Parolai  Sandra M. Richwalski  Lothar Stempniewski 《Natural Hazards》2006,38(1-2):229-236

Ambient seismic noise measurements were conducted inside the Cathedral of Cologne (Germany) for assessing its frequencies of vibration and for checking whether these occur in the range where soil amplification is expected. If this is the case, damages may increase in case of an earthquake due to an increased structural response of the building. Analysis of the ratio between the horizontal and vertical components of the spectra recorded at stations located inside the building as well as the ratio between the corresponding components of the spectra recorded simultaneously inside the building and at a reference station placed in the basement of the cathedral indicated several modes of vibration. Facilitated by these results an assessment of the seismic vulnerability was attempted for a 2D ground motion scenario using the finite element method.  相似文献   

New Generation of Probabilistic Seismic Hazard Assessment for the Area Cologne/Aachen Considering the Uncertainties of the Input Data     

G. Grünthal  R. Wahlström 《Natural Hazards》2006,38(1-2):159-176

A new earthquake catalogue for central, northern and northwestern Europe with unified M_w magnitudes, in part derived from chi-square maximum likelihood regressions, forms the basis for seismic hazard calculations for the Lower Rhine Embayment. Uncertainties in the various input parameters are introduced, a detailed seismic zonation is performed and a recently developed technique for maximum expected magnitude estimation is adopted and quantified. Applying the logic tree algorithm, resulting hazard values with error estimates are obtained as fractile curves (median, 16% and 84% fractiles and mean) plotted for pga (peak ground acceleration; median values for Cologne 0.7 and 1.2 m/s² for probabilities of exceedence of 10% and 2%, respectively, in 50 years), 0.4 s (0.8 and 1.5 m/s²) and 1.0 s (0.3 and 0.5 m/s²) pseudoacclerations, and intensity (I₀ = 6.5 and 7.2). For the ground motion parameters, rock foundation is assumed. For the area near Cologne and Aachen, maps show the median and 84% fractile hazard for 2% probability of exceedence in 50 years based on pga (maximum median value about 1.5 m/s²), and 0.4 s (>2 m/s²) and 1.0 s (about 0.8 m/s²) pseudoaccelerations, all for rock. The pga 84% fractile map also has a maximum value above 2 m/s² and shows similarities with the median map for 0.4 s. In all maps, the maximum values fall within the area 6.2–6.3° E and 50.8–50.9° N, i.e., east of Aachen.  相似文献   

T -distributed Random Fields: A Parametric Model for Heavy-tailedWell-log Data1     

Jo R?islien  Henning Omre 《Mathematical Geology》2006,38(7):821-849

Histograms of observations from spatial phenomena are often found to be more heavy-tailed than Gaussian distributions, which makes the Gaussian random field model unsuited. A T-distributed random field model with heavy-tailed marginal probability density functions is defined. The model is a generalization of the familiar Student-T distribution, and it may be given a Bayesian interpretation. The increased variability appears cross-realizations, contrary to in-realizations, since all realizations are Gaussian-like with varying variance between realizations. The T-distributed random field model is analytically tractable and the conditional model is developed, which provides algorithms for conditional simulation and prediction, so-called T-kriging. The model compares favourably with most previously defined random field models. The Gaussian random field model appears as a special, limiting case of the T-distributed random field model. The model is particularly useful whenever multiple, sparsely sampled realizations of the random field are available, and is clearly favourable to the Gaussian model in this case. The properties of the T-distributed random field model is demonstrated on well log observations from the Gullfaks field in the North Sea. The predictions correspond to traditional kriging predictions, while the associated prediction variances are more representative, as they are layer specific and include uncertainty caused by using variance estimates.  相似文献   

参数在线自调整模糊控制算法研究     

谌洪茂  贾宏伟  黄国辉 《华东地质学院学报》2006,29(3):277-282

针对间歇式热处理炉温度控制对象的特性要求,提出了参数在线自调整模糊控制与智能积分相结合的一种新型模糊控制方法。该方法的基本思想是在系统误差较大时,用参数在线自调整模糊控制算法以提高系统的响应;在系统误差较小时,加入智能积分作用以消除静态误差,智能积分作用是有选择的施加积分作用,克服了一般连续积分控制的缺点。论述了带智能积分参数在线自调整模糊控制器的设计及软件实现。并且通过在MATLAB软件上的仿真分析表明该方法的合理性及可行性。  相似文献