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931.
根据东天山及邻区地层、沉积建造、构造岩石组合、变形、变质、古生物分区、深部地壳结构、地球物理、地球化学特征,以康古尔塔格-黄山深断裂为界,划分了不同级别的构造单元和构造沉积相带。统计分析了202个金属矿床,重点研究了金、银、铜、镍、钼、铁等矿产空间分布与板块构造、碰撞带关系,划分出九个成矿带,三个成矿期,以海西中晚期最为显著。成矿与板缘构造活动带地质演化密切相关,与俯冲一碰撞带和韧性剪切带时空演化最为密切。构造分区控制的矿产成带性和构造演化形成的成矿集中期之间相互转化对该区金属矿产有重要控制作用。  相似文献   
932.
本文介绍了地幔柱理论研究的一系列进展,诸如地幔柱特征、动力学模式及其一系列地质效应;阐明了地幔柱构造与板块构造的关系。地幔柱理论涉及的是地幄深部物质垂直运动的机制,其研究对于进一步了解地球深部动力学机制有重大意义。  相似文献   
933.
一种基于差分投影的汽车牌照自动识别方法   总被引:2,自引:0,他引:2  
针对汽车牌照的特点,利用差分投影法对汽车图像进行处理,确定出牌照的准确位置并将其整体切割下来;然后利用差分投影法对牌照进行切分,切分出待识别的车牌字符;再利用模板匹配的方法对切分出的车牌字符进行识别.实践证明该方法对汽车牌照的自动识别非常有效.  相似文献   
934.
A lattice Boltzmann automaton (LBA) is used as a modelling approach to investigate the influence of pore‐space geometry on intrinsic processes and component distributions in recent tidal sediments. The simulations are performed on real pore‐space structures obtained from scanning electron photomicrographs, which document the mesoscopic geometry of bioactive sandy surface sediments. The discrete transport–reaction model for dissolved oxygen shows that in advective controlled systems oxygen concentration properties can be clearly related to the pore‐space geometry. Variability of measured high‐resolution concentration gradients can therefore can be attributed to the structural heterogeneity of pore‐space geometry. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
935.
吉林深震的构造背景和区域地震能量的异常讨论   总被引:1,自引:0,他引:1  
从吉林深震的形成与板块构造活动的关系入手,介绍了深震与吉林省区域构造活动背景的联系。利用测震学活动性指标,讨论了发震前后区域地震能量时空变化的特点,并结合对前兆资料的分析,得出了深震前后区域地震能量的累积与释放的特点。本文试图阐明异同,探讨机制,以期对地震活动规律的研究有所帮助。  相似文献   
936.
Long distance detection of electron anti-neutrinos from reactors at distances of order 200 km has been achieved with the 1000 ton liquid scintillator-based KamLAND instrument in Japan. In summer 2005 the KamLAND group reported the first detection of anti-neutrinos from the natural radioactivity of the earth. These measurements are due to uranium and thorium decays dominantly from the nearby crust in Japan, and are expected to have only a small contribution from the earth’s mantle (and core). Several new detectors are under consideration around the world for measurements which when taken together can reveal the location of these heavy elements, which are expected to contribute a major share of the internal earth’s heating via their radioactivity. This heating is of course associated with providing the power to drive the geomagnetic field and plate tectonics. Geologists have only indirect evidence about the deep earth, mostly from seismic wave velocity and inferences from a few meteorites. Anti-neutrino detection, on the other hand, yields direct information about earth’s interior. The location and magnitude of the earth’s uranium and thorium are crucial to understanding the origin and evolution of the earth and present day activity. Lead Article in Proceedings of Neutrino Sciences 2005  相似文献   
937.
The present study focuses on the hydraulic behaviour of joints, and, specially, on its numerical implementation in terms of the FEM analysis using a discrete fracture flow approach. Fluid flow through discontinuities has traditionally been modelled using special elements of zero-thickness, which we can classify into single, double and triple-nodded. Single node elements are the simplest and consist of ‘line’ or ‘pipe’ elements which are superimposed onto the standard continuum mesh and that can only model the longitudinal conductivity through the discontinuity. On the other hand, some authors have included the influence of a transversal conductivity, and the subsequent localized potential drop, by using triple node interface elements. In those, the two nodes of the adjacent continuum elements represent the potentials in the pore system on each side of the interface, and a third node in the middle represents the average potential of the fluid in the channel represented by the discontinuity. Finally, double node interface elements have also been proposed, which have the advantage of making it possible to use the same FE mesh for both mechanical and flow analysis. In some cases the influence of a transversal conductivity is not considered and, therefore, although geometrically double-nodded, these elements belong to the single node type and when time comes to solve the system the two nodes must have the same potential, which can only be obtained by the ‘trick’ of prescribing the equivalence of these two d.o.f. before solving the global system of equations. This limitation may, however, be avoided by assuming that the potential in the channel is the average of the two sides of the interface. Based in this simple assumption, an alternative flow interface model has been recently developed and implemented, which preserves both longitudinal and transversal conductivities. An application example is developed and solved with the three types of interfaces described. The results offer useful information regarding the range of applicability and limitations of the new double-nodded interface element proposed. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
938.
介绍了基于圆柱摆体和圆弧柱面极板的二维倾斜仪模型,并对其圆弧柱面差动电容电路进行理论分析。结果表明,提高倾斜仪的观测灵敏度需适度增加圆柱摆体半径与高度及吊丝长度,减小圆弧柱面极板圆心角,缩小动极板与定极板间隙距离;减少倾斜仪的输出非线性需适度增加圆柱摆体半径和动极板与定极板间隙距离,减小圆弧柱面极板圆心角、圆柱摆体高度及吊丝长度。依据该原则,选取一组典型参数,计算得到倾斜仪理论灵敏度为0.028 5 V/(″),非线性度为0.001 2%。  相似文献   
939.
《国际泥沙研究》2022,37(5):539-552
A detailed analysis of horizontal and vertical particulate matter (PM) fluxes during wind erosion has been done, based on measurements of PM smaller than 10, 2.5, and 1.0 μm, at windward and leeward positions on a measuring field. The three fractions of PM measurement are differently influenced by the increasing wind and shear velocities of the wind. The measured concentrations of the coarser fractions of the fine dust, PM10, and PM2.5, increase with wind and shear velocity, whereas the PM1.0 concentrations show no clear correlation to the shear velocity. The share of PM2.5 on PM10 depends on the measurement height and wind speed and varies between 4 and 12 m/s at the 1 m height ranging from 25% to 7% (average 10%), and at the 4 m height from 39% to 23% (average 30%). Although general relationships between wind speed, PM concentration, and horizontal and vertical fluxes could be found, the contribution of the measuring field was very low, as balances of incoming and outgoing fluxes show. Consequently, the measured PM concentrations are determined from a variety of sources, such as traffic on unpaved roads, cattle drives, tillage operations, and wind erosion, and thus, represent all components of land use and landscape structure in the near and far surroundings of the measuring field. The current results may reflect factors from the landscape scale rather than the influence of field-related variables. The measuring devices used to monitor PM concentrations showed differences of up to 20%, which led to considerable deviations when determining total balances. Differences up to 67% between the calculated fluxes prove the necessity of a previous calibration of the devices used.  相似文献   
940.
沿海吹填砂土地基地下水位较高、常含软土夹层,地基处理难度大。为了研究高能级强夯在这类吹填砂土地基上的加固效果,在山东沿海某吹填砂土场地开展6 000和8 000 kN·m能级强夯加固试验。试验结束后分别运用标准贯入试验、静力触探试验、平板载荷试验进行现场检测。通过对比分析了设计要求深度范围内标准贯入试验和静力触探试验,发现夯前夯后标准贯入试验击数和静力触探锥尖试验阻力均明显提升,有效消除了饱和砂土和饱和粉土的液化势;通过平板载荷试验p-s曲线及夯后静力触探锥尖阻力标准值与承载力特征值的关系式,得到夯后砂土地基承载力特征值≥120 kPa,验证了高能级强夯方案的可行性。其次,对软土夹层位置和地下水位高度展开研究,发现软土层会阻碍夯击能传递,减小强夯有效加固深度,且软土层位置不同对强夯加固效果影响程度不同,强夯影响临界范围处存在软土层时,有效加固深度为软土层顶部位置处;对砂土地基进行4 000 kN·m能级强夯试验时,发现未降水强夯后有效加固深度为5 m,降水至地面以下3 m强夯后有效加固深度达到了7 m,提高了加固效果。在高能级强夯研究基础上,对现场吹填砂土地基进行了75万m2的大面积高能级强夯施工,发现处理后地基能够满足建筑用地要求。  相似文献   
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