波列在时、空域的数值模拟试验及波要素的统计比较     

杨日石  蒋信利  王景林 《海洋学研究》2008,26(3):62-70

利用Longuet-Higgins 波浪模型,分别用无因次JONSWAP谱和文圣常谱生成时间序列的表面波列与其相匹配的空间序列表面波列,作波浪特征波要素间关系的数值试验检验.由实测资料核对表明,以往有关工程上应用的理论和经验关系有的可信度高,有的似应作改进,特别不能将在时间序列上得到的有关经验数据贸然用在空间序列的表面波上.  相似文献   

Two-phase flow properties of a horizontal fracture: The effect of aperture distribution     

《Advances in water resources》2015

A systematic numerical method has been presented to investigate the constitutive relationships between two-phase flow properties of horizontal fractures and aperture distributions. Based on fractal geometry, single rough-walled fractures are generated numerically by modified successive random addition (SRA) method and then aperture distributions with truncated Gaussian distribution are formed by shear displacement between lower and upper surfaces. (The truncated Gaussian distribution is used to describe aperture evolution under different normal stresses.) According to the assumption of two-dimensional porous media and local parallel plate model, invasion percolation approach is employed to model the two-phase flow displacement (imbibition) in generated horizontal fractures, in which capillary forces are dominant over viscous and gravity forces. For truncated Gaussian distributions, constitutive relationships from numerical simulation are compared to closed-form relationships and a good agreement is obtained. The simulation results indicate strong phase interference with the sum of two phase relative permeability values being less than one in the intermediate saturations. It is found that fracture properties related to residual saturations depend on spatial correlation of aperture distributions. Based on the simulation results, we proposed an empirical relationship between the fracture residual-saturation-rated parameters and the corresponding aperture distributions.  相似文献   

Using Stressor–Response Models to Derive Numeric Nutrient Criteria for Lakes in the Eastern Plain Ecoregion,China          下载免费PDF全文

Yali Zhang  Shouliang Huo  Chunzi Ma  Xiang Li  Hongliang Liu 《洁净——土壤、空气、水》2014,42(11):1509-1517

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The influence of landscape connectivity and landslide dynamics upon channel adjustments and sediment flux in the Liwu Basin,Taiwan          下载免费PDF全文

Cheng‐Wei Kuo  Gary Brierley 《地球表面变化过程与地形》2014,39(15):2038-2055

Catchment‐scale analyzes of spatial and temporal variability in landscape connectivity are critical considerations in appraisals of landscape evolution and disaster mitigation in tectonically active mountain belts such as Taiwan. This study uses historical aerial photographs, flow discharge and seismic data to analyze landslide changes and channel adjustments over a 30 year period in the Liwu Basin. Recurrent earthquakes and typhoon events trigger frequent landslide activity, channel adjustment and sediment reworking in this system. Spatial variability in magnitude–frequency relations of hillslope‐valley floor (lateral) and upstream–downstream (longitudinal) connectivity during the study period are shown to reflect annual reworking in source and accumulation zones, while partly‐confined valleys in the mid‐catchment area trap sediment behind landslide‐induced dams that are formed and breached on an approximately decadal basis. This promotes partial longitudinal connectivity in these areas. Landscape responses to disturbance events were especially pronounced following combinations of seismic and typhoon events prior to the 1998 and 2005 images. Although single high magnitude events and series of moderate events affect patterns of landscape connectivity in the Liwu Basin, residence times for sediment storage are very short in this highly‐connected river system, where confined valley settings extend virtually to the coast. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Seismic ground motion relationships in southern China based on stochastic finite-fault model     

郑斯华  黄玉龙 《地震工程与工程振动(英文版)》2004,3(1)

The characteristics of seismic ground motions in southern China are difficult to determine statistically due to a lack of strong ground motion data. In this study, a stochastic finite-fault ground motion model was adopted to simulate the seismic ground motions at bedrock for southern China, based on parameters derived from small and medium earthquakes that have occurred in the region. From these, the response spectra was estimated. A set of ground motion attenuation relationships was then developed based on simulated peak ground motions and response spectral parameters through regression, which would be applicable for use in engineering practice. Through comparisons, it was demonstrated that the proposed ground motion relationships are generally consistent with those obtained from other reported ground motion attenuation models for southern China.  相似文献   

三维地层建模钻孔数据预处理研究   总被引：2，自引：0，他引：2  

夏艳华  白世伟 《岩土力学》2012,33(4):1223-1239

钻孔数据是三维地层建模的主要数据来源之一,在三维地层建模中,地层界面一般基于钻孔数据插值而成,正确处理钻孔数据是构建理想三维地层模型的前提和基础。三维地层拓扑关系极其复杂,地层界面插值数据在数学上选择也不是惟一的,因此,常导致构建地层模型出现与事实相悖的情形。针对这一点,根据地层地质演变历史,建立地层层序序列,此序列记录地层地质年代顺序及其拓扑关系。根据地层地质特征,可将地层拓扑关系概化为两类：“覆盖”和“侵蚀”。据此地层层序序列可惟一确定地层界面插值数据,从而构建正确地层模型。采用python语言实现了该钻孔数据预处理算法,实例表明,该预处理方案能正确地预测实际地层。  相似文献   

空间数据挖掘的地理案例推理方法及试验   总被引：2，自引：0，他引：2  

杜云艳  温伟  曹锋 《地理研究》2009,28(5):1285-1296

从空间数据挖掘的角度谈地理案例推理方法,认为地理案例推理是面向问题的一种空间数据挖掘方法。针对这一思想进行了基于地理案例的空间数据挖掘具体算法介绍。首先在明确地理案例具体定义的基础上,给出了面向问题的空间数据挖掘地理案例界定和组织方法;其次,鉴于地理空间的自然地带性和区域分异性规律的影响,深入探讨了地理案例自身或其间所可能存在的相互依赖和相互制约关系,并给出了采用粗糙集方法进行地理案例内蕴空间关系的定量挖掘方法;第三,针对地理案例表达时考虑的空间特征和空间关系的不同,给出了三种状况下的空间相似性计算模型;最后,以土地利用这一典型的地学现象为例,给出具体实例,一方面进行土地利用问题的定量分析与推测;另一方面,通过实例展示地理案例推理方法在地学问题求解以及空间数据定量分析上的特点和优势。  相似文献   

Modeling elements and geographical factors of formation of the monthly runoff as exemplified by the Kuda river     

A.V. Ignatov  N.V. Kichigina 《Geography and Natural Resources》2010,31(4):396-402

We have formulated the main principles of constructing the model for a seasonal cycle of the runoff with a temporal resolution of one month. We worked out the elements of technology for the first stages of model making. Based on analyzing the local data on monthly characteristics of the runoff, precipitation and temperature, we formulated and verified a number of hypotheses about the physicalgeographical patterns of formation of seasonal and interannual variability in water flow rates for three river discharge sections within the Kuda river basin. The most important factors have been determined, which govern the observed values of monthly mean flow rates.  相似文献   

宁夏区域震源参数特征研究     

张锦玲  朱新运  马起杨  金春华 《大地测量与地球动力学》2017,37(8):808-812

利用宁夏区域数字地震台网记录的发生于宁夏区域2008～2014年210个ML2.0～4.9地震波资料,采用Brune模式,将台站获取的速度记录进行几何扩散校正、介质衰减校正及仪器校正,对速度谱在频率域积分得到震源位移谱,使用遗传算法计算拐角频率及零频极限,进而计算震源半径、地震矩等小震震源参数,并系统分析各参数特征及其相互关系。结果显示,地震矩范围为1011～1015 N·m,震源破裂半径为60～766 m,拐角频率为1.6～22.2 Hz,地震应力降范围为0.01～7.63 MPa,视应力范围为0.01～3.11 MPa,地震矩、拐角频率、矩震级及里氏震级等震源参数之间表现出一定的对数线性或半对数线性关系。  相似文献   

面向模型的大比例尺制图综合框架设计与实现   总被引：9，自引：0，他引：9  

应申  郭仁忠  闫浩文  林亨贵 《测绘学报》2002,31(4):344-349

模型综合作为制图综合的一部分 ,是通过改变地图内部目标关系的表达方式 ,使地图的表达更简单 ,进而使综合更方便。结合交互式制图综合软件AutoMap ,介绍了面向模型综合的系统设计框架和具体实现 ,并着重从地图目标的空间关系、几何属性和语义关系 3个方面来分析模型综合。  相似文献