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在前人研究基础上,对Groom-Bailey(GB)张量分解畸变因子和区域阻抗的求解方法进行了改进.首先,通过Swift旋转与GB分解的扭变和剪切矩阵的求逆变换,利用变换后区域阻抗主对角元素为0的条件获得关于扭变因子和剪切因子的超定方程组,采用模拟退火全局优化算法进行求解.其次,由得到的扭变因子和剪切因子,结合Swift旋转确定的走向角和区域阻抗元素的估计,作为非线性最小二乘局部优化算法的初始值,对GB分解定义式的超定方程组进行求解,得到各畸变参数和区域阻抗的解.通过模型试验验证了方法的正确,对方法的稳定性进行了比较与评价,并通过与已有结果的对比和实际资料的应用,表明了方法实际应用的效果. 相似文献
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北京市地铁暗挖施工沉降控制探讨 总被引：1，自引：0，他引：1
仅以北京市地铁4#线张自忠车站主体暗挖施工的沉降监控项目为研究背景,对穿越城市主干道的车站结构暗挖施工进行连续性的沉降变形监测;从地下构筑物暗挖施工的工序变化与地表沉降的关系进行试验研究.在预测基础上对获取的数据进行多层次的统计与分析,以研究其变形规律与稳定性,实现了信息化施工. 相似文献
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Inhomogeneous aggregates of late-stage titanite enriched in Zr have been described recently from post-magmatic parageneses in silica-undersaturated rocks. In the natural samples, simple isovalent substitution of the large Zr ([vi]R4+=0.72 Å) for Ti ([vi]R4+=0.605 Å) is limited to an empirical maximum of 0.25 afu (15.3 wt.% ZrO2). As the natural material is not suitable for crystallographic study, a series of CaTi1-xZrxOSiO4 titanite samples have been synthesized by standard ceramic methods at ambient pressure in air, and their crystal structure determined by Rietveld refinement of laboratory powder X-ray diffraction patterns. All of the synthetic Zr-doped titanite varieties adopt space group A2/a and consist of distorted CaO7 polyhedra together with less distorted (Ti1-xZrx)O6 octahedra and SiO4 tetrahedra. Cell dimensions and atomic coordinates together with volumes and distortion indices are given for all polyhedra. The empirical limit for Zr substitution in synthetic (F,OH)-free titanite is 0.5 afu (29.6 wt.% ZrO2). The existence of a Zr analogue of titanite in nature is considered to be unlikely. 相似文献
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当地表存在三维非均匀电导率分布时,区域大地电磁响应发生畸变. 以往对这种畸变研究多假设近地表为三维,区域构造为一维或二维. 对于更一般的三维/三维构造,为了分析并消除这种畸变影响,真实反映地下三维区域构造信息,本文实现了三维大地电磁相位张量积分方程数值算法,并研究在不同地质模型下相位张量响应. 结果表明,相位张量不仅可以反映一般三维构造信息,亦可有效反映复杂近地表构造下三维区域构造信息,而无须假设区域构造为一维或二维,证明相位张量具有较强抗近地表局部非均匀构造干扰能力,能够保持更为一般的三维区域构造信息. 为了加快正演计算,同时保持一定精度,算法采用了积分方程多网格法. 相似文献
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The topographic mapping products of airborne light detection and ranging (LiDAR) are usually required in the national coordinates (i.e., using the national datum and a conformal map projection). Since the spatial scale of the national datum is usually slightly different from the World Geodetic System 1984 (WGS 84) datum, and the map projection frame is not Cartesian, the georeferencing process in the national coordinates is inevitably affected by various geometric distortions. In this paper, all the major direct georeferencing distortion factors in the national coordinates, including one 3D scale distortion (the datum scale factor distortion), one height distortion (the earth curvature distortion), two length distortions (the horizontal-to-geodesic length distortion and the geodesic-to-projected length distortion), and three angle distortions (the skew-normal distortion, the normal-section-to-geodesic distortion, and the arc-to-chord distortion) are identified and demonstrated in detail; and high-precision map projection correction formulas are provided for the direct georeferencing of the airborne LiDAR data. Given the high computational complexity of the high-precision map projection correction approach, some more approximate correction formulas are also derived for the practical calculations. The simulated experiments show that the magnitude of the datum scale distortion can reach several centimeters to decimeters for the low (e.g., 500 m) and high (e.g., 8000 m) flying heights, and therefore it always needs to be corrected. Our proposed practical map projection correction approach has better accuracy than Legat’s approach,1 but it needs 25% more computational cost. As the correction accuracy of Legat’s approach can meet the requirements of airborne LiDAR data with low and medium flight height (up to 3000 m above ground), our practical correction approach is more suitable to the high-altitude aerial imagery. The residuals of our proposed high-precision map projection correction approach are trivial even for the high flight height of 8000 m. It can be used for the theoretical applications such as the accurate evaluation of different GPS/INS attitude transformation methods to the national coordinates. 相似文献
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通过象山港水域的潮波运动数值模拟,分析了象山港M4分潮的生成和增长机制．结果说明,潮波传播中的非线性底摩擦效应是M4分潮生成和增长的主要控制因子,M4分潮在湾内的共振现象也起着重要的放大作用二平流效应在绝大部分区域中抑制了M4分潮的发展,只有在佛渡水道中一些岛屿周围极小区域内对M4分潮有增强作用．潮滩在湾内对M4分潮的影响极其微弱． 相似文献
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将PE方法与地震数值模拟方法相结合研究了中尺度涡影响下目标地层成像的畸变.模拟了不同声源频率、不同水深条件下的地震波场.计算结果发现,中尺度涡的存在使得真实地形结构无法在地震成像中反映,而且地震成像畸变随着海水深度、震源频率的增加而增大.机理分析表明,中尺度涡所带来的水体温度梯度变化是产生地震成像畸变的主要因素.为了便于工程应用,本文还推导了有效涡强度、温度差与地形畸变率的关系式.本文的研究结果将对提高深海地震成像精度有一定的指导意义. 相似文献
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震前应变固体潮畸变的物理模式 总被引：1，自引：0，他引：1
本文根据岩石力学及固体潮理论，建立了孕震期弹性物体应变固体潮的物理模式，给出了其数学公式。通过分析潮汐应力与寻震应力的合力随潮汐力相位的变化，从物理本质上讨论了不同应力阶段应变固体潮曲线的形态特征；讨论了震前不同异常时期，应变固体潮畸变的不同特．点；并对震例进行了分析，同时，对应变固体潮畸变与地震三要素预报作了初步探讨。 相似文献
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