基于Kriging估计的GPS高程转换

随着GPS测量精度的不断提高,其平面测量已经在多种领域得到应用,成为测量工作的一个全新的手段与工具,但在GPS测高方面需要改善和研究。Kriging方法是地统计学的基本方法,其理论核心是变异函数,它是一种最好的线性无偏估计法,在地理学、生态学、环境科学等领域都得到了广泛的应用,取得了很好效果。本文在详细介绍kriging法的基础上,建立了Kriging法的GPS高程拟合模型,利用该模型对两个实例的GPS高程数据拟合,得到了正常高,结果表明Kriging法在GPS高程拟合中的应用精度达到厘米级,且得出了一些有益的结论,为以后GPS高程的应用提供一些参考。     

自适应多尺度第二代小波配点法探地雷达数值模拟

基于第二代小波变换的提升方案构造了插值小波,将雷达波场函数进行了二维小波变换,得到所有尺度上与计算网格相联系的小波系数和尺度系数.对所有尺度上的小波系数进行分析,根据解的局部性与小波系数阈值的控制,实现网格压缩和配点的自适应调节.保留大于给定阈值的小波系数及对应网格点,令小于给定阈值的小波系数为零,并舍弃其对应网格点.达到光滑区域采用较少的计算网格点,在奇异性较大的区域采用较多的计算网格点的目的.通过对自适应网格进行邻域校正、重构检查等附加修正,推导了场值更新的显式时间迭代方案.最后,以均匀、阶梯与复杂三个典型GPR模型为例,与常规数值计算结果对比表明：自适应小波配点法（AWCM）利用第二代小波的多尺度分解和快速变换的特点,可以使计算网格随着时间步适应解的移动和变化,允许计算资源更有效地使用,具有高压缩率,达到跟踪奇异性的目的,特别适合于探地雷达正演中波传问题的模拟.

     

离散光滑插值方法在地球物理位场中的快速实现

研究并探讨了1种新的插值方法-离散光滑插值方法及其在地球物理位场中的快速实现.首先由待插值点与已知点之间的拓扑关系建立线性约束,进一步结合位场满足Laplace方程,建立离散光滑插值联立方程组,采用预条件共轭梯度求解该方程组.为更好地提高计算效率,在求解过程中采用螺旋坐标系和Wilson-Burg谱分解,将二维数据转换到一维空间处理.通过理论模型和实际资料计算,该方法适合地球物理位场特征,插值效果好,速度快.     

多连通域中的插值序列

本文给出了多连通域(由有限个连续统所界)上点列为H~∞(D)插值序列的几个等价条件。这些条件是保形不变的。     

Three-dimensional RITSS large displacement finite element method for penetration of foundations into soil

The Remeshing and Interpolation Technique with Small Strain (RITSS) approach has been developed to deal with 3-D geotechnical problems in this paper. Unstructured 20-node hexahedral element is found to work well for predicting collapse loads accurately for 3-D undrained geotechnical problems involving material incompressibility. Remeshing is automatically accomplished by ANSYS program. With remeshing and interpolation, small fluctuations appear in the load–deformation results. In order to minimize these fluctuations, different increment sizes and remeshing frequencies are explored. Meanwhile, various 3-D interpolation methods are compared, and the unique element division method is found to work best. The results of two numerical applications are presented for a 3-D strip footing penetrating deeply into uniform clay and a square foundation into normally consolidated clay. The computed bearing capacity responses are compared with other numerical or conventional results. The results show that the present method is accurate and efficient for 3-D large displacement foundation penetration problems.     

GPS网络RTK系统的内插算法研究

本文详细介绍了GPS网络RTK系统中内插算法的基本原理和计算公式，并进行了模拟计算，从而验证了内插算法的精度和可靠性。     

Mapping optimization based on sampling size in earth related and environmental phenomena

A critical sampling grid can be defined for an earth related natural variable distributed in space, according to established theoretical results and under certain mathematical conditions. Sampling above this critical limit does not substantially improve mapping results, while based on this limit the ideal process of reproducing the original phenomenon is theoretically defined. The aim of the present paper is, by using an innovative approach; to investigate the validity of commonly used interpolation algorithms, both stochastic and deterministic, below and above this critical sampling limit. When sampling is dense, application to a simulated spatial random field shows that the results are equally accurate with those derived with more sophisticated stochastic methods. On the other hand, when the sampling grid is sparse, deterministic methods produce less accurate results, therefore stochastic algorithms with minimum estimation error are a much better option. To further demonstrate these points, the interpolation algorithms were applied in three different sampling grid densities in a contaminated waste disposal site in Russia.     

局部动态最优Voronoi图的NNI算法及其在格网数字水深模型中的应用

在分析传统自然邻点插值(NNI)算法局限性的基础上,依据Voronoi单胞和Delaunay三角形的几何特性,提出基于局部动态最优Voronoi图的NNI算法。阐述该算法的基本原理和实现步骤,并在VC++环境下结合多波束测深数据对其在格网数字水深模型(Grid-DDM)中的应用进行了验证。试验表明该算法具有执行效率高、插值精度不丢失等优点。     

The development of a historical digital cadastral database†

With an ever-increasing number of land information systems being developed, there is a growing demand by users for systems which support the use of temporal data for time-based studies. System managers, however, may have difficulty responding to these calls because of the lack of available research to guide them in their task. This paper examines the simple method of storing and processing temporal graphical data by the addition of time-encoding attributes to data elements as required. To illustrate the technique, a historical digital cadastral database has been created which al lows users to display and report on the cadastral parcellation of a region at any time in the past. The method can also be widely applied to other data to assist a broad range of space/time-related studies.     

An algorithm for interpolation in the pyramid domain‡

With the pyramid transform, 2D dip spectra can be characterized by 1D prediction‐error filters (pefs) and 3D dip spectra by 2D pefs. These filters, contrary to pefs estimated in the frequency‐space domain (ω, x) , are frequency independent. Therefore, one pef can be used to interpolate all frequencies. Similarly, one pef can be computed from all frequencies, thus yielding robust estimation of the filter in the presence of noise. This transform takes data from the frequency‐space domain (ω, x) to data in a frequency‐velocity domain (ω, u=ω·x) using a simple mapping procedure that leaves locations in the pyramid domain empty. Missing data in (ω, x) ‐space create even more empty bins in (ω, u) ‐space. We propose a multi‐stage least‐squares approach where both unknown pefs and missing data are estimated. This approach is tested on synthetic and field data examples where aliasing and irregular spacing are present.