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71.
72.
刘林清 《华东地质学院学报》2001,24(4):273-276
通过遥感图像地质解译,发现崇安地区存在一较大的环状构造。经区域地质分析和野外验证,该环状构造始成于加里东期,以后又有多次活动,燕山晚期活动最强。在环状构造的影响下,形成了古楼-床沙透镜状地质体,成为该区铀矿化分布的区域控制因素,从而形成一个独立的成矿单元。其中铀矿化和异常片的分布大致显示了中心对称和两翼对称特点,成矿远景好,今后应深入加强深部找矿工作。 相似文献
73.
针对多波束点云数据去噪难以保留精细特征,无法精确“锁定”河床形态问题,本文提出了一种面向自然资源确权水流三维登记探索的多波束点云去噪算法。以KD树搜索为基础,引入统计滤波理论进行多尺度噪声分类,并剔除大尺度噪声;针对小尺度噪声,在信息熵理论基础上,以主成分分析算法为基础,以信息熵最小原则确定最优邻域,并据此构建曲率信息熵对双边滤波因子进行优化改进,以实现水下地形点云去噪与精细特征保留的目的。试验结果表明,本文算法具有可行性,能够有效保证水下地形的精细特征,并能够应用于自然资源水流三维登记。 相似文献
74.
会议密钥的管理与分发是设计安全网络会议系统的关键问题之一。利用基于拉格朗日插值多项式的会议密钥分发方案,借鉴逻辑密钥层次树结构设计了1种会议密钥分发方案。在每次举行会议时,会议主席根据用户树计算参会者子树,利用参会者子树的根结点公钥构造拉格朗日插值多项式。减少了会议主席构造拉格朗日插值多项式的次数和计算开销。特别地,对构造的会议系统,当参会者的人数超过一定数目时,会议主席构造拉格朗日插值多项式的次数会随着参会者人数的增加而减少。另外,每个用户的私钥保持不变,避免了用户私钥的更新过程。 相似文献
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76.
Lead rubber bearings, which have been extensively applied in many seismic isolation designs for buildings, infrastructures, and facilities worldwide, were tested under unilateral reversal loading as well as nonproportional plane loading including circular, figure-eight, and square orbits in this study. The test results indicate that unlike the unilateral hysteretic behavior, the bilateral one of lead rubber bearings is too complicated to be characterized adequately by a simplified bilinear hysteretic model. It is mainly attributed to the bilateral coupling effect, which can be clearly observed from the abnormal deformation of the mesh pattern drawn on the rubber cover during the tests. In addition, after being subjected to nonproportional plane loading, the tested bearings reveal visible permanent twisting deformation. The profiles of the cut bearings present the fracture of the inside lead plugs. Even so, the further unilateral reversal loading test results prove that the fracture might not affect the whole hysteretic behavior and mechanical properties very much. The applicability, robustness, and generalization of adopting three previously developed analytical models for describing the coupled bilateral hysteretic behavior of lead rubber bearings are further demonstrated by comparing their predictions with the nonproportional plane loading test results. Although the coefficients are identified from unilateral reversal loading tests, the three analytical models can still have an acceptable prediction capability. 相似文献
77.
城市二级光电测距三角高程导线精度分析 总被引:1,自引:1,他引:0
本文对城市二级光电测距三角高程导线的误差来源进行了分析,并对其精度进行估算。根据实例分析,证明了城市二级光电测距高程导线可以代替五等水准测量。 相似文献
78.
铅芯叠层橡胶支座恢复力模型研究 总被引:5,自引:0,他引:5
在Wen和Park模型的基础上,对铅芯叠层橡胶支座单向和双向耦合恢复力模型进行了改进,使其可以更为准确的模拟铅芯叠层橡胶支座单向和双向耦合的滞回性能。并由计算分析可以看出,考虑双向耦合作用与未考虑双向耦合作用的恢复力滞回曲线有较大差别,因而支座应采用双向耦合恢复力模型以考虑支座的双向耦合作用对结构地震反应的影响。 相似文献
79.
80.
Sampling for microfossils in exploratory wells in basins with hydrocarbon potential is subject to considerable uncertainty,
mainly because the samples usually are small and subject to caving. Biostratigraphic events defined on fossil taxa include
their last occurrences of which the depths along the wells generally can be measured with precision. The RASC method for ranking
and scaling of stratigraphic events produces an average basin-wide optimum sequence and zonation that can be used for correlation
of strata between wells. In this optimum sequence the fossil events are ordered according to their occurrences in geological
time. Depth differences between successive events in the optimum sequence satisfy a frequency distribution that is of interest
for potentially increasing stratigraphic resolution. In this article the depth difference frequency distribution is modeled
for three large Cenozoic microfossil data sets consisting of 30 wells in the North Sea Basin, 27 wells on the Labrador Shelf
and Grand Banks, and 11 wells in the western Barents Sea. The shapes of the three frequency distributions satisfy bilateral
gamma distributions with similar parameters. These distributions are fitted by the construction of straightlines on normal
Q–Q plots of square root transformed average-corrected depth differences. The gamma distribution model is approximately satisfied
except for small negative and positive depth differences, which have anomalous frequencies because of the discrete sampling
method used in exploratory well-drilling to collect microfossils. It implies not only comparable average stratigraphic order
of events, but also comparable average sedimentation rates in the three Cenozoic basins selected for study. 相似文献