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排序方式: 共有113条查询结果,搜索用时 15 毫秒
31.
将分形理论应用到探地雷达 (GPR)资料处理解释中 ,以提高探地雷达剖面的分辨率。通过建立相应的GPR的fBm模型 ,采用逐次随机增加方法 (SuccessiveRandomAdditions)对GPR数据进行细分。实验分析表明 ,分形处理是一种提取GPR高分辨率信息的非常有效的方法 ,其效果要比常规处理 (如线性滤波等 )明显 ;最后用分形技术对实际探地雷达检测剖面进行了处理 ,取得了较好效果 相似文献
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靳盛海 《水文地质工程地质》1993,20(6):28-29,59
本文推导了二维非稳定流渗流场不同等级网格有限差分理论方法。概述了这种方法比以往其它有限差分方法的优越性。并用算例进行了验证。 相似文献
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35.
县域耕地保有量目标约束机制及预测研究——以广西灌阳县为例 总被引:8,自引:2,他引:6
区域差异性导致各地耕地保护的目标不同,县域耕地保有量预测目标是否合理关系到区域和全局的耕地保护压力程度,影响着耕地保有量的合理预测,对有效遏止圈地现象至关重要。在耕地外部性特征基础上提出耕地保有量外部性连环效应,并据此效应建立县域耕地保有量预测目标约束机制;通过分析灌阳县在上轮规划耕地保护情况和耕地保有量现状,将灌阳县耕地保有量预测目标定位为耕地均量动态平衡;预测规划目标年灌阳县耕地保有量目标及相关单项指标。 相似文献
36.
采用改进型逐次逼近解法(MSAM)和Aitken加速技术相结合的迭代算法计算二维积分方程.该算法将纵向成层原状地层作为背景地层,将计算区域限制在井眼和侵入带内,具有未知量数目少、收敛速度快、计算精度高的优点.利用该算法对随钻电磁波电阻率测量仪器在轴对称二维地层中的响应进行数值模拟.模拟结果显示,幅度衰减曲线和相位移曲线受井眼、侵入和围岩的影响程度不同,二者径向探测深度和垂向分辨率也有差异,利用补偿后的幅度衰减电阻率曲线和相位移电阻率曲线交叉点的坐标可精确确定地层层界面位置. 相似文献
37.
Building structures damaged by a seismic event may be exposed to the risk of aftershocks or another event within a certain period. In this paper, the seismic assessment of damaged piloti‐type RC buildings was carried out to evaluate probabilistic retrofitting effects under successive earthquakes. First, a framework to evaluate the effectiveness of retrofitting was proposed, and then the proposed methodology was demonstrated with a structure retrofitted with buckling‐restrained braces (BRBs). For consideration of realistic successive earthquakes, past records measured at the same station were combined. Within the framework, a series of nonlinear time history analyses were performed for an as‐is model subjected to single earthquake, a damaged model subjected to successive earthquakes, and a damaged model retrofitted with BRBs subjected to successive earthquakes. In addition, fragility analysis was systematically applied in the framework for evaluation of effectiveness of the retrofitting strategy. The proposed framework was capable of quantifying the influence of successive earthquakes and evaluating the effectiveness of BRB retrofitting by considering the severity of the first earthquake damage and the hysteresis behavior of the retrofit element. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
38.
Palaeo-karst collapse pillars in northern China and their damage to the geological environments 总被引:4,自引:0,他引:4
According to statistics, there are a total of 39 sites of palaeo-karst collapse pillars in Northern China, as well as 3,650
palaeo-karst collapse pillars. Through an overall survey and analysis of the distribution regularities and formation mechanisms
of palaeo-karst collapse pillars in the northern coal mine regions, this paper found that the rock formation structures, geological
structures, karst characters, underground hydrodynamic conditions of karst and neotectonic movement conditions are basic geological
bases for the formation of karst collapse pillars and rule the distribution of them. Karst collapse pillars apparently have
three south–north regularities in terms of distribution, and they have resulted in severe damages to geological resources
and environment in their distribution areas: mine water inrush causing and coal resources damage and influencing the impounding
of reservoirs as well as the stability of dam sites. Based on the basic geological features of palaeo-karst collapse pillars
in northern China, this paper also introduces the new methods of integrated prospecting of successive approximation to determine
hydraulic conductivity of palaeo-karst collapse pillars. 相似文献
39.
为了充分展示和利用全国镍矿预测的思路及其主要成果,本文根据矿产预测类型的划分标准,将镍矿划分为岩浆型镍-铜硫化物矿、风化壳型镍矿和海相沉积型镍-钼-钒矿3种类型,并系统总结了各矿产预测类型的基本特征、成矿规律、利用现状、预测要素和预测方法。在此基础上,对中国镍矿从成矿地质背景、地球化学特征、矿床分布密集程度、成矿强度以及资源潜力方面进行了分析与综合,结合矿床类型特点,提出了喀拉通克、觉罗塔格、北山、辽吉、龙首山、祁曼塔格、墨江—金平和宝坛等8个战略接续区,用以指导镍矿找矿工作部署。 相似文献
40.
Framework of aftershock fragility assessment–case studies: older California reinforced concrete building frames 下载免费PDF全文
Current seismic design codes and damage estimation tools neglect the influence of successive events on structures. However, recent earthquakes have demonstrated that structures damaged during an initial event (mainshock) are more vulnerable to severe damage and collapse during a subsequent event (aftershock). This increased vulnerability to damage translates to increased likelihood of loss of use, property, and life. Thus, a reliable risk assessment tool is required that characterizes the risk of the undamaged structure subjected to an initial event and the risk of the damaged structure under subsequent events. In this paper, a framework for development of aftershock fragilities is presented; these aftershock fragilities define the likelihood that a building damaged during a mainshock will exhibit a given damage state following one or more aftershocks. Thus, the framework provides a method for characterizing the risk associated with damage accumulation in the structure. The framework includes the following: (i) creation of a numerical model of the structure; (ii) characterization of building damage states; (iii) generation of a suite of mainshock–aftershocks; (iv) mainshock–aftershock analyses; and (v) development of aftershock fragility curves using probabilistic aftershock demand models, defined as a linear regression of aftershock demand–intensity pairs in a logarithmic space, and damage‐state prediction models. The framework is not limited to a specific structure type but requires numerical models defining structural response and linking structural response with damage. In the current study, non‐ductile RC frames (low‐rise, mid‐rise, and high‐rise) are selected as case studies for the application of the framework. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献