时空数据模型的N1NF关系基础   总被引：25，自引：4，他引：25  

黄明智  张祖勋 《测绘学报》1997,26(1):1-6

Ｎ１ＮＦ关系方法在处理非表格化的复杂结构对象时优于传统关系方法，因而适合于时态ＧＩＳ。本文讨论了空间对象的Ｎ１ＮＦ表达和操作，将空间，时间和属性结合为一个整体，与作者的前期工作一起构成了矢量式时空数据模型的Ｎ１ＮＦ关系基础；本文还初步讨论了建立在这个基础上的面状地理要素的时空数据模型。  相似文献   

Geometry of risk analysis (morphogenetic system)     

Germano Resconi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(4):425-432

We know that risk analysis is based on the estimation of catastrophic events. Now to obtain a good estimation we must create suitable model of the risk. With samples of data we can use different mathematical models as linear or non linear regression methods, neural network methods, genetic methods and more recent hybrid models consisting of the information diffusion approximate reasoning method and back propagation neural network. In this paper, we present a new frame-work denoted morphogenetic system to study risk analysis. We show that morphogenetic system is a generalization of the tensor calculus used to formalize the non Euclidean geometrical representation. Now, we take suggestion from the electrical circuit analysis to create the morphogenetic model for the estimation. In the electrical circuit, we have the vector of voltages and vector of currents. The relation between voltages and currents is given by Ohms rule and the impedance matrix. The relation is a multi input and multi output (MIMO) system given a set of samples for voltages and currents we can estimate the impedance matrix of the circuit. Now, we know that the electrical circuit is controlled by a limited set of voltage or current sources. The aim of this papers is to give the rule by which from arbitrary voltages in the circuit we compute the voltage sources and also the associated current sources. We also give the method to compute the currents by the current sources and also the voltages by the impedance matrix. All the process from arbitrary voltages, voltage sources, current sources, current in the circuit and voltage in the circuit is denoted the projection operator in the morphogenetic system. Electrical circuits are a prototype of the morphogenetic system. We show that fuzzy inferential processes can be modeled by morphogenetic systems to improve models to estimate risks.  相似文献   

Noise suppression for microseismic data by non‐subsampled shearlet transform based on singular value decomposition          下载免费PDF全文

Xiaoqiang Liang  Yue Li  Chao Zhang 《Geophysical Prospecting》2018,66(5):894-903

The existence of strong random noise in surface microseismic data may decrease the utility of these data. Non‐subsampled shearlet transform can effectively suppress noise by properly setting a threshold to the non‐subsampled shearlet transform coefficients. However, when the signal‐to‐noise ratio of data is low, the coefficients related to the noise are very close to the coefficients associated with signals in the non‐subsampled shearlet transform domain that the coefficients related to the noise will be retained and be treated as signals. Therefore, we need to minimise the overlapping coefficients before thresholding. In this paper, a singular value decomposition algorithm is introduced to the non‐subsampled shearlet transform coefficients, and low‐rank approximation reconstructs each non‐subsampled shearlet transform coefficient matrix in the singular value decomposition domain. The non‐subsampled shearlet transform coefficients of signals have bigger singular values than those of the random noise, which implies that the non‐subsampled shearlet transform coefficients can be well estimated by taking only a few largest singular values. Therefore, those properties of singular value decomposition may significantly help minimise overlapping of noise and signals coefficients in the non‐subsampled shearlet transform domain. Finally, the denoised microseismic data are obtained easily by giving a simple threshold to the reconstructed coefficient matrix. The performance of the proposed method is evaluated on both synthetic and field microseismic data. The experimental results illustrate that the proposed method can eliminate random noise and preserve signals of interest more effectively.  相似文献   

EXPERIMENTAL STUDY ON AGGRADATION     

E.ALVES  A.H.CARDOSO 《国际泥沙研究》1999,(1)

１ＩＮＴＲＯＤＵＣＴＩＯＮＨｕｍａｎａｃｔｉｖｉｔｉｅｓｍａｙｉｎｄｕｃｅｓｉｇｎｉｆｉｃａｎｔｃｈａｎｇｅｓｉｎｓｅｄｉｍｅｎｔｔｒａｎｓｐｏｒｔｃａｐａｃｉｔｙｏｆａｌｕｖｉａｌｒｉｖｅｒｃｈａｎｎｅｌｓａｎｄｃａｕｓｅｃｈａｎｇｅｓｉｎｔｈｅ...  相似文献   

非地转湿Q矢量及其在华北特大台风暴雨中的应用   总被引：33，自引：2，他引：31  

姚秀萍  于玉斌 《气象学报》2000,58(4):436-446

在非地转 Q矢量的基础上 ,考虑天气系统发展的主要热力强迫因子——非绝热加热作用 ,引入非地转湿 Q矢量的概念 ,并推导出其表达式以及用非地转湿 Q矢量散度为唯一强迫项所表示的非地转ω方程。同时 ,用非地转湿 Q矢量分析方法诊断了由北上台风倒槽引起的一次华北特大暴雨过程 ;结果表明 ,非地转湿 Q矢量能较清楚地揭示暴雨过程系统的演变 ;通过比较非地转湿 Q矢量、垂直速度和不考虑“湿”过程的“干”Q矢量散度与暴雨落区的配置关系 ,结果发现 ,非地转湿 Q矢量与降水落区存在最佳的对应关系 ,非地转湿 Q矢量散度负值区能较好地预报出未来 6h的降水落区 ,而且其中心数值的大小与未来 6h降水的强度存在正相关的对应关系 ,从而说明非地转湿 Q矢量对于暴雨天气系统诊断和预报是一种十分有效的工具 ,其散度负值区可以作为未来 6h降水落区预报的重要指标 ,为暴雨的预报提供了更广阔的思路  相似文献   

Attitude stability of artificial satellites subject to gravity gradient torque     

Rodolpho Vilhena de Moraes  Regina Elaine Santos Cabette  Maria Cecília Zanardi  Teresinha J. Stuchi  Jorge Kennety Formiga 《Celestial Mechanics and Dynamical Astronomy》2009,104(4):337-353

The stability of the rotational motion of artificial satellites is analyzed considering perturbations due to the gravity gradient torque, using a canonical formulation, and Andoyer’s variables to describe the rotational motion. The stability criteria employed requires the reduction of the Hamiltonian to a normal form around the stable equilibrium points. These points are determined through a numerical study of the Hamilton’s equations of motion and linear study of their stability. Subsequently a canonical linear transformation is used to diagonalize the matrix associated to the linear part of the system resulting in a normalized quadratic Hamiltonian. A semi-analytic process of normalization based on Lie–Hori algorithm is applied to obtain the Hamiltonian normalized up to the fourth order. Lyapunov stability of the equilibrium point is performed using Kovalev and Savchenko’s theorem. This semi-analytical approach was applied considering some data sets of hypothetical satellites, and only a few cases of stable motion were observed. This work can directly be useful for the satellite maintenance under the attitude stability requirements scenario.  相似文献   

抚顺××厂万m~3储油罐地基沉降的综合治理     

仲大维  姬国海 《国土资源》1997,(1)

抚顺××厂３＃万ｍ３储油罐自１９９０年以来，罐体基础持续产生不均匀沉降。围绕该储油罐，通过高压定喷施工工艺，构筑定喷桩，地下防渗连续墙，在墙体内侧对罐体地基进行冲积层及基岩的直、斜孔注浆，用水泥浆液充填、胶结地基中的空化、裂隙，提高了地基强度，对减缓罐体的不均匀沉降，取得了显著成效。  相似文献   

基于无定向导线实施地下过江顶管工程定位及其精度的研究   总被引：1，自引：1，他引：0  

潘庆林 《测绘工程》2000,9(2):55-58

从理论与实践上对基于无定向导线实施地下过江顶管的定位及其精度进行了研究 ,指出在有利条件下基于无定向导线是传递方向有效且精度较高的方法。  相似文献   

基于长时段非线性影响分析的冬小麦产量预报   总被引：5，自引：0，他引：5       下载免费PDF全文

王叔同  张荣霞 《应用气象学报》2000,11(3):377-382

为提高冬小麦产量预报的准确性、稳定性, 通过气象产量与气象因子的膨化相关普查, 筛选出长时段、非线性因子组建预报方程, 收到了预期的效果.经4年的使用验证及与其他几种统计方法的比较, 该方法预报结果较为理想, 可用于基层台站的冬小麦产量预报.  相似文献   

地形与纬向切变基流中的非线性Rossby波   总被引：1，自引：0，他引：1       下载免费PDF全文

何建中 《热带气象学报》1993,9(2):177-184

在半地转近似下,用相角函数方法得到了含地形强迫作用与纬向切变基流的非线性常微分方程.利用微分方程解的几何定性理论,直接得到该方程存在有限振幅的周期波与孤立波解的存在条件.利用函数逼近法求得波解的显式解,得到了一些有意义的结果。  相似文献