Classical Scattering and Block Regularization for the Homogeneous Central Field Problem

The present paper offers an alternative point of view of block regularization for the motion of a particle in a central potential field of the form –x ^–, where x is the distance between the particle and the source and some positive real number.Working in the physical space, we consider the scattering angle determined by the path of the particle as a function of angular momentum. We prove that a particle flow is passing over the collision singularity preserving differentiability with respect to initial data if and only if = 2(1–1/n), n positive integer, n 2.This result coincides with the outcome of block regularization applied by McGehee to the same dynamical problem. We discuss that this identity was to expect since both methods target the same physical constraint over the flow.     

Time‐harmonic response of non‐homogeneous elastic unbounded domains using the scaled boundary finite‐element method

The scaled boundary finite‐element method is extended to simulate time‐harmonic responses of non‐homogeneous unbounded domains with the elasticity modulus and mass density varying as power functions of spatial coordinates. The unbounded domains and the elasticity matrices are transformed to the scaled boundary coordinates. The scaled boundary finite‐element equation in displacement amplitudes are derived directly from the governing equations of elastodynamics. To enforce the radiation condition at infinity, an asymptotic expansion of the dynamic‐stiffness matrix for high frequency is developed. The dynamic‐stiffness matrix at lower frequency is obtained by numerical integration of ordinary differential equations. Only the boundary is discretized yielding a reduction of the spatial dimension by one. No fundamental solution is required. Material anisotropy is modelled without additional efforts. Examples of two‐ and three‐dimensional non‐homogeneous isotropic and transversely isotropic unbounded domains are presented. The results demonstrate the accuracy and simplicity of the scaled boundary finite‐element method. Copyright © 2005 John Wiley & Sons, Ltd.     

The most homogeneous dip-scanning method using edgepreserving smoothing for seismic noise attenuation

Highlighting and analyzing the geological features of faults and fractures in seismic data is particularly important for hydrocarbon exploration and exploitation since they are often essential for finding and delineating reservoirs. We apply edge-preserving smoothing （EPS） to seismic processing and propose a most homogeneous dip-scanning method. The method preserves the geological features, eliminate random noise efficiently, obtain dip information, and improve the accuracy of identifying the oil and gas traps.     

MATHEMATICAL MODEL FOR SEDIMENT TRANSPORT CAPACITY OF HYPERCONCENTRATED FLOW

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A Doubly Weighted Approach to Urban Data Disaggregation in GIS: A Case Study of Wuhan, China

Urban models are evolving to require more and more detailed data that in many cases have to be spatially disaggregated from larger zones. This paper deals with the disaggregation of statistical data in an urban context in which land use data are available at a less detailed level. With the availability of land use data, the traditional approach of areal weighting is improved with an areal and land use weighted approach. This weighted approach is further elaborated to include homogeneous weight zones (HWZ) so as to reflect general geographical variations among the same land use type. A case study in Wuhan, China has demonstrated the effectiveness of the doubly weighted approach within the specified context.     

基于相交直线的相对定向方法

提出了一种基于相交直线的相对定向方法,提取同名相交直线特征,根据相交条件方程获得相对定向元素。该方法完全不需要同名点数据,能够解决因同名点不足而无法准确定向的问题。通过航空影像、近景影像和倾斜影像的实验表明,该方法能够获得稳定的相对定向结果。采用本文提出的算法与传统的相对定向方法进行联合平差,能够进一步提高相对定向结果的精度和稳定性。     

SVD方法在场分析和预测中的应用

由预报场与因子场的奇异值分解（SVD），可找到影响预报场的主要物理因子，能提取两个场相互作用的主要耦合信号，借助最优化技术，可实现由因子场对预报场的客观预报，以华中汛期降水场为左场，4月北半球500hPa高度场，海平面气压场，北太平洋海温场组成右场，进行SVD分析和预报试验，其结果令人满意。     

时间序列均生函数模型在降水量预测中的应用

利用高要站1980—2015年冬季(12月—次年2月)的降雨量,构建均生函数模型,并采用粗选因子、逐步引入、逐步剔除等3组回归方案,对降雨量进行模型拟合,2016—2017年冬季降雨量进行模型预测结果的检验。结果表明:3组回归方程均能较好地拟合时间序列的变化趋势,对极值的把握表现较好,对短期气候预测业务有一定的现实意义。     

一种建筑群同质二元组直线模式的识别方法

建筑群空间分布模式识别对制图综合、多尺度表达及空间数据挖掘具有重要意义.针对建筑群中以建筑物组合结构为单元的直线模式识别问题,提出一种建筑群同质二元组直线模式的识别方法.首先分析研究同质二元组直线模式的认知特征和定义;然后利用Delaunay三角网构建建筑群邻近关系,以建筑物邻近性、尺寸和方向相似性约束进行聚类,考虑邻...     

位移-应变模型的稳健均匀分析

运用稳健估计法确定应变模型的特殊位移,识别影响均匀应变的特殊位移参数,用实例分析验证了作者提出了稳健的均匀分析法的有效性。