三维复杂层状介质中多震相走时联合反演成像   总被引：8，自引：5，他引：3       下载免费PDF全文

白超英  黄国娇  李忠生 《地球物理学报》2011,54(1):182-192

采用新近提出的改进型不规则最短路径多次波射线追踪正演技术,结合共轭梯度法求解带约束的阻尼最小二乘最优化反演问题,讨论了三维复杂层状模型中利用多震相走时资料进行联合反演成像的技术方法.考虑到不同震相种类走时的拾取误差不同,反演算法中引入了不同震相种类数据的权系数;另外,考虑到同时反演速度模型和反射界面起伏中不同参数变化对...  相似文献   

声波定向随钻对接钻井技术及其运用     

熊斌辉 《海洋地质译丛》2014,(1):86-91

常规的钻井导向技术测量是钻头的空间方位,误差与钻井深度成正比,不能满足随钻井眼直接对接要求.与常规钻井导向技术不同,声波定向随钻对接钻井技术是在靶点测量安装在钻挺的声波发生器的声波时差确定钻头与靶点的相对方向.钻头与靶点越近,测量精度越高,对接时误差小于1 cm.对接钻井技术省事、省时、省钱,在对接钻井、防碰钻井、重叠钻井、平行钻井等各种特殊钻井领域有广泛地运用价值.  相似文献   

International low carbon technology transfer: Do intellectual property regimes matter?     

《Global Environmental Change》2014

Transfer of low carbon technologies to developing countries has been recognized as important in global efforts to limit climate change. Yet the mechanics of international technology transfer, especially around intellectual property rights, have remained a controversial issue in international negotiations. Using a new dataset on international partnerships in China and India in three key low carbon technologies—solar photovoltaics, electric vehicles, and coal gasification/integrated gasification combined cycle—and complementary expert interviews we study the dynamics of the transfer of intellectual property and the underlying drivers that guide the development of business strategies and partnerships in the context of transitioning intellectual property regimes in emerging markets. We find that weak intellectual property regimes are indeed a hindrance to the diffusion of certain classes of low carbon technologies: (i) for cutting-edge technologies, (ii) for fully-embodied (explicitly codified) technologies, and (iii) for small firms. However, we also find that intellectual property issues do not represent a barrier to the diffusion of the relatively mature and low to medium cost low carbon technologies that are materially (at scale) most important for carbon dioxide emissions reduction in the short to medium term. Competitive technology supply, shifting market dynamics, and increasingly vigorous domestic innovation coupled with mechanisms and opportunities to structure credible intellectual property deals allow for the diffusion of key low carbon technologies to occur within the context of existing business, political, and institutional structures.  相似文献   

Column-generation kernel nonlocal joint collaborative representation for hyperspectral image classification     

《ISPRS Journal of Photogrammetry and Remote Sensing》2014

We propose a kernel nonlocal joint collaborative representation classification method based on column generation for hyperspectral imagery. The proposed approach first maps the original spectral space to a higher implicit kernel space by directly taking the similarity measures between spectral pixels as a feature, and then utilizes a nonlocal joint collaborative regression model for kernel signal reconstruction and the subsequent pixel classification. We also develop two kinds of specific radial basis function kernels for measuring the similarities. The experimental results indicate that the proposed algorithms obtain a competitive performance and outperform other state-of-the-art regression-based classifiers and the classical support vector machines classifier.  相似文献   

Mapping Human Terrain in the Joint Army–Navy Intelligence Study of Korea (1945)     

Seung-Ook Lee  Trevor Barnes  Joel Wainwright 《The Professional geographer》2013,65(4):663-675

The concept of human terrain has become a prominent element of U.S. military strategy. It is a means to capture the cultural–geographical qualities of an enemy or target population. An early effort to map human terrain is found in the Joint Army–Navy Intelligence Study (JANIS) of Korea (1945). We argue that the JANIS report on Korea was paradigmatic for the U.S. military's contemporary geographical work and offers insights into the cultural politics of human terrain mapping. This explains why the JANIS text is cited by the National Geospatial-Intelligence College (NGC) today as an historical model. This article not only offers a window into the history of geography counterinsurgent but also shows that geography has been entwined with empire.  相似文献   

Will you escort your child to school? The effect of spatial and temporal constraints of parental employment     

《Applied geography (Sevenoaks, England)》2013

Children's independent mobility in many urban areas in the United States has been in decline. This implies that children's out-of-home travel involves the company of adults more often than before. This need requires parents to seek ways to balance work-family life. This study examines the factors that influence a parent-child joint trip to school in dual-earner households, with special consideration given to parental work arrangements and location, which act as intra-household temporal and spatial constraints. The study is carried out in the five-county Los Angeles region, drawing from household travel diaries from the 2001 Southern California Association of Governments (SCAG) Post Census Regional Household Travel Survey. The results show that parental employment, especially the mother's, is a very important factor influencing the probability of a joint trip to school. In terms of temporal constraints, longer working hours will reduce the likelihood that a child will be escorted by its parents. However, the option of flexible work hours offsets the negative effect of long working hours by offering a higher degree of scheduling flexibility. In terms of spatial constraints, the closer the mother's workplace is to the school, the more likely it is that the child will be escorted by the parents. This research provides important evidence that a child's joint trip is heavily influenced by the parents' work schedule and location. The findings shed light on how the provision of certain employment policies and programs may affect joint trips to school.  相似文献   

基于自适应遗传算法的MRS-TEM联合反演方法研究   总被引：2，自引：2，他引：0       下载免费PDF全文

万玲  林婷婷  林君  蒋川东  嵇艳鞠 《地球物理学报》2013,56(11):3728-3740

地面磁共振法(MRS)因具有定性、定量分析地下水能力,而备受关注.传统磁共振地层含水量反演多采用均匀半空间模型,忽略电阻率分布信息对结果的影响.针对这一问题,本文基于多层电介质中磁共振响应理论,提出MRS与瞬变电磁(TEM)联合反演方法,通过电阻率分布信息对含水量反演过程的实时修正,提高了解释结果的准确度.反演算法采用自适应遗传算法(AGA)进行,基于繁殖规则,动态调整交叉概率和变异概率,解决了标准遗传算法易未成熟收敛而难以得到全局最优解问题.模型数据表明,含噪10%情况下,联合反演仍能较准确地反映地下含水单元模型结构,对比MRS单独反演优势明显.同时,内蒙古白旗野外观测数据联合反演结果与钻井资料基本一致,充分验证了AGA反演算法的实用性及MRS-TEM联合反演的实际意义.  相似文献   

P波和S波接收函数的贝叶斯联合反演          下载免费PDF全文

王峻  刘启元 《地球物理学报》2013,56(1):69-78

S波接收函数对于研究岩石圈速度结构具有重要价值. 本文利用合成地震图技术研究了S波接收函数的动力学特征. 在接收函数非线性复谱比反演方法的基础上,发展了基于贝叶斯理论的P波和S波接收函数的非线性联合反演方法. 结果表明:(1)适用于S波接收函数反演的震中距范围约为55°~80°,S波接收函数反演要求所用远震事件的震级大于5级; (2)与陡变的岩石圈底部界面(LAB)相比,梯度带类型LAB上生成的S_LP转换波相对较弱,台站下方的沉积盖层有助于相对增强S_LP震相; (3)由于S波接收函数径向分量不符合δ脉冲,不依赖于等效震源假定的三分量接收函数多道最大或然性反褶积方法更适合S波接收函数的估计;(4)数值检验的结果表明,在初始模型速度参数偏离真实模型20%的情况下,本文的方法能够预测300 km深度范围内的P波和S波速度结构;(5)观测数据的反演结果表明,由于P波接收函数低频分量相对不足,本文的联合反演方法对于大于100 km深度上地幔的S波速度结构约束相对较弱.  相似文献   

S-wave velocity structure in the SE Tibetan plateau          下载免费PDF全文

Yan Cai  Jianping Wu  Weilai Wang  Lihua Fang  Liping Fan 《地震科学（英文版）》2016,29(3):165-172

We use observations recorded by 23 permanent and 99 temporary stations in the SE Tibetan plateau to obtain the S-wave velocity structure along two profiles by applying joint inversion with receiver functions and surface waves. The two profiles cross West Yunnan block(WYB),the Central Yunnan sub-block(CYB), South China block(SCB), and Nanpanjiang basin(NPB). The profile at ~25°N shows that the Moho interface in the CYB is deeper than those in the WYB and the NPB, and the topography and Moho depth have clear correspondence.Beneath the Xiaojiang fault zone(XJF), there exists a crustal low-velocity zone(LVZ), crossing the XJF and expanding eastward into the SCB. The NPB is shown to be of relatively high velocity. We speculate that the eastward extrusion of the Tibetan plateau may pass through the XJF and affect its eastern region, and is resisted by the rigid NPB, which has high velocity. This may be the main cause of the crustal thickening and uplift of the topography. In the Tengchong volcanic area, the crust is shown to have alternate high- and low-velocity layers, and the upper mantle is shown to be of low velocity. We consider that the magma which exists in the crust is from the upper mantle and that the complex crustal velocity structure is related to magmatic differentiation. Between the Tengchong volcanic area and the XJF, the crustal velocity is relatively high.Combining these observations with other geophysical evidence, it is indicated that rock strength is high and deformation is weak in this area, which is why the level of seismicity is quite low. The profile at ~23°N shows that the variation of the Moho depth is small from the eastern rigid block to the western active block with a wide range of LVZs. We consider that deformation to the south of the SE Tibetan Plateau is weak.  相似文献   

基于精确Zoeppritz方程的非线性AVO三参数反演          下载免费PDF全文

周林  李景叶  陈小宏 《地球物理学报》2016,59(7):2663-2673

常规AVO三参数反演通常存在密度反演不准确的问题,而密度参数对常规油气藏中的流体识别、流体饱和度计算、孔隙度计算以及非常规油气藏中TOC含量计算、裂缝预测等都至关重要,因此对于研究如何利用大偏移距振幅信息和富含密度信息的PS波地震资料来提高密度反演结果的稳定性和精度显得尤为重要.研究基于贝叶斯反演理论框架,引入三变量Cauchy分布先验约束,利用精确Zoeppritz方程构建了AVO三参数联合反演的目标函数,对目标函数进行Taylor二阶非线性简化,得到模型参数的迭代更新公式,实现了大偏移距地震振幅信息的利用和PP波、PS波联合反演.合成数据和实际地震数据的方法测试结果表明,新方法不仅可以直接反演纵波速度、横波速度和密度,而且还具有很高的精度,尤其是密度反演结果.基于合成数据的PP波、PS波单独反演结果与PP波和PS波联合反演结果对比显示,联合反演稳定性更好,精度更高,抗噪能力更强,验证了该方法的可行性和有效性.与基于Aki-Richards近似公式的反演结果对比表明,该反演方法具有更高的反演精度和更好的抗噪性.  相似文献