共查询到20条相似文献，搜索用时 93 毫秒
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利用有限正弦和有限余弦变换模拟地震波场:声波方程 总被引：4，自引：1，他引：3
研究了一种利用有限正弦和有限余弦变换解变密度声波方程的方法,它的基本思想有下列4点：(1)对声波方程两端进行关于一个或多个变量的有限正弦或有限余弦变换;（2）将待求波场的Fourier正弦或余弦级数表达式代入到经过变换后的波动方程之中,进而得到级数表达系数所满足的微分方程式;（3）分别对时间和未作变换的空间导数进行有限差分或其它形式的近似,得到变换系数所满足的离散（矩阵）方程;（4）将通过解离散（矩阵）方程而得到的变换系数代入到相应的反演公式中去,用求和的方式得到待求波场的数值解。与其它方法相比,利用有限正弦和有限余弦的优点在于可以无限制地扩展变换方向的计算区间和可以处理任意变化的速度和密度结构而不明显地增加计算量。 相似文献
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利用小波变换检测超声成象测井图象边缘的研究 总被引：1，自引：1，他引：1
对超声成象测井图象中的小波变换边缘的检测方法进行了研究。介绍了小波变换边缘检测的原理 ,阐述了基于小波变换模极大值的超声成象测井图象边缘检测的算法 ,最后给出了应用实例。实践表明 :利用小波变换检测超声成象测井图象边缘的检测方法 ,可有效地弥补传统边缘检测算法的不足 ,在有效地抑制噪声的同时 ,提高了检测细小边缘成分的精度。该方法可以从不同尺度下的边缘图象中检测出不同细节的地质特征 ;小尺度下的检测结果可用于分析超声成象测井图象中的地质体的细小结构 ,大尺度下的检测结果可用于分析超声成象测井图象的地质体的整体结构 相似文献
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YAN Jun HAO Xue WANG Zhao-guo College of GeoExploration Science Technology Changchun China 《吉林大学学报(地球科学版)》2006,(Z2)
对于任意信号,在MSE意义上最优的信号估计是Wiener滤波器。小波变换在时域和频域上同时具有局部化特征,在信号处理中得到了广泛应用。论证了小波域上Wiener滤波器的设计,提出了应用的方法。 相似文献
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七十年代初期就有人把积分变换理论中的希尔伯特变换方法引入到重磁场解释领域[2],后来逐渐进一步用于磁异常的定量解释。方法的基本特点都是利用磁异常曲线与其希尔伯特变换曲线的特殊特征交点,导出求解地质体的埋藏深度等参数解析表达式。然而,在实践应用中,上述方法有局限性。因为要得到理想的特征点是困难的,而且只利用个别点求出的参数其可靠程度也较差,特别是在解释区域磁测资料时,要求在每个测点上(或者任意点上)都能得到其地质体的产状参数。为此,我们提出一种在任意点上求解地质体产状参数的方法,以扩展上述方法的应用范围。这就是本文介绍给读者的目的。 相似文献
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《物探化探计算技术》1980,(1)
前言最近文献中刊载了一种快速计算任意形状物体重磁异常的富氏变换法,其基本原理如下: 具有均匀密度或均匀磁化强度分布的任意形状物体的重力与磁力异常均可表示为场源几何形状函数与格林函数的褶积。因此,它们的频谱可以表示为这两个函数的富氏变换的乘积。要计算物体引起的重磁异常,关键在于给出格林函数与场源几何形状的富氏变换,然后再对这两个函数的富氏变换的乘积作反富氏变换。场源几何形状由描述物体形状的解析式给出,格林函数则仅与观测点的位置和磁化强度矢量或密度有关,而与场源的几何形状无关。所以,对于某种场位来说,只要一次 相似文献
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提出了一种基于小波变换的图像加水印及检测的新方法,即对图像文件进行二维多尺度离散小波变换,得到图像数据高频和低频部分。在高频部分数据中,加入随机数水印并进行图像重构,检测时以同样方法进行小波分解,检测高频部分与随机数水印的相关性。此方法可用于图像防伪。 相似文献
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为了在时频域刻画裂缝等边缘信息及其多尺度特征,构造了一种新的广义S变换分频边缘检测。它借鉴了小波多尺度边缘检测的思想,利用广义S变换的时频局部谱,通过不同频率尺度滤波达到突出与定位不同尺度边缘信息的目的。模型信号处理表明：广义S变换分频边缘检测方法既能准确刻画边缘奇异信息,又能反映边缘的多尺度特征,具有与小波多尺度边缘检测相似的特点。利用这一方法对实际地震资料处理的结果表明,它可以在不同频率尺度情况下有效检测断层、裂缝发育带的几何形态和空间展布。 相似文献
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徐宝慈 《物探化探计算技术》1990,12(1):21-28
本从位场理论出发，推导了连续变量条件下任意形体位场的希尔伯特变换，导出了几种规则二度体磁场的希尔伯特变换解析表达式。在总结磁场垂直分量、水平分量及其希尔伯特变换之间的关系的基础上。讨论了由离散希尔伯特变换值反演地质体形状、确定座标原点，曲线切点座标的方法原理。为实现利用位场资料用计算机连续、自动反演产状参数提供了一种新的可行途径，基于大量模型实验结果，在辽东湾油气远景评价项目中，应用希尔伯特变换方法反演了磁性岩深度，结合其它地质、物探资料的综合解释，对判定生油沉积厚度，追索断裂、构造单元走向、圈定含油气远景区，提供了有意义的信息。 相似文献
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各向异性砂土K0试验研究 总被引：1，自引：0，他引：1
静止土压力系数K0是岩土工程分析计算中的重要力学参数之一。实际工程中墙后填土由于碾压都具有不同程度的各向异性。制备了不同沉积方向的砂土试样,通过三轴排水剪切试验研究了砂土的各向异性。在研制应变路径试验设备的基础上给出了静止土压力系数的测量方法,研究了不同沉积方向对于K0的影响,并将试验测得的静止土压力系数与Jaky公式以及土压力离心模型试验结果进行了对比,离心模型试验结果与材料单元试验结果一致,证明了测量方法的有效性及结果的正确性。研究结果表明,各向异性条件下的K0值比各向同性时明显偏大。 相似文献
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本文依据前人的理论基础,在总结分析激电法找油的地球物理前提条件下,开展了该方法的试验兼生产工作,取得了令人满意的效果,并进一步证实了激电法找油的异常模式。 相似文献
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本文依据前人的理论基础，在总结分析激电法找油的地球物理前提条件下，开展了该方法的试验兼生产工作，取得了令人满意的效果，并进一步证实了激电法找油的异常模式。 相似文献
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关于用室内三轴(CD)试验方法确定基床系数的探讨 总被引：1，自引：0，他引：1
根据基床系数的理论结合现场平板载荷试验方法结果,对用室内三轴(CD)试验测定基床系数测定结果的处理方法进行分析。 相似文献
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Characteristics of the Mesozoic and Cenozoic Tectonic Stress Fields of the Urumqi-Usu Region, Xinjiang 总被引：1，自引：0，他引：1
Tao Mingxin Lanzhou Institute of Geology Academia Sinic Beijing Jiang Minxi 《《地质学报》英文版》1993,67(1):17-31
Based on the study of folds and related conjugate shear joints, the tectonic stress fields of the Urumqi-Usu region to the north of the North Tianshan Mountains have been reconstructed. Furthermore the author discussed the tectonic movements and their dynamic features. The early tectonic movement in the investigated region occurred from the end of the Late Jurassic to the initial stage of the Early Cretaceous, with the maximum (tensile) and minimum (compressional) principal stress trajectories in the tectonic stress field being in E-W and S-N directions respectively; the late tectogenesis took place from the end of the Early Pleistocene to the initial Middle Pleistocene, with the maximum and minimum principal stress trajectories in the late stress field striking in WNW and NE-NNE directions respectively. Through computer-aided simulated calculation by the finite element method and analysis of geological structure, it has been ascertained that the early tectogenesis is a nearly N-S compressive movement and the late one a NE to nearly N-S compressive movement with reverse shear. The dynamic force which caused the tectogeneses came from the movement of the southern major fault, i.e. the North Tianshan Mountains. 相似文献
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Jrgen Liboriussen 《Sedimentary Geology》1973,10(4):249-260
A new technique for the long-axis fabric analysis of oriented till samples is presented. This method is based on the study of X-ray radiographs, which can be interpreted either directly or with the help of a microscope. An area in eastern Jylland (Jutland), Denmark, which was glaciated during the Weichselian, was selected to test this method and compare it with other known methods of studying the directions of ice flow, such as the macroscopic fabric analysis and other field observations. 相似文献
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Incorporation of fracture directions into 3D geostatistical methods for a rock fracture system 总被引：2，自引：2，他引：0
Simulating a rock fracture distribution is an important problem common to various fields in geosciences. This paper presents GEOFRAC, a geostatistical method to simulate a fracture distribution by incorporating the directions (strikes and dips) of the sampled fracture data into the simulation. Fracture locations are generated randomly following fracture densities assigned by a sequential Gaussian simulation. Fracture directions are transformed into an indicator set consisting of several binary (0 and 1) variables and the variables are compressed using the principal component analysis. Ordinary kriging is then employed to estimate the distributions of these principal values and the results are back-transformed into the coordinate system of the original indicator set. Fracture directions are generated randomly using their histograms within the defined directional interval. Finally, facets (fracture elements) are determined from the simulated locations and directions, and the fractures within the angle and distance tolerances are connected to form a fracture plane. From a case study of applying GEOFRAC to the fracture data in Kikuma granite, southwest Japan, GEOFRAC was shown to be able to depict a plausible fracture system because the simulated directions corresponded well to those measured. Furthermore, the simulated fracture system was available to estimate the hydraulic conductivity of the study site, which was roughly in agreement with the average of hydraulic test results. 相似文献
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Studies made on the anisotropy of magnetic susceptibility of artificial sediments have shown that there are correlations between the orientation of anisotropy axes and of transport directions. Thus, the analysis of parameters of anisotropy of magnetic susceptibility can constitute a means to investigate transport directions in flysch. To test this method in a natural model, the authors have made some measurements on flysch beds belonging to the “grés d'Annot complex”. The sediments have been sampled in the Contes and Peira-Cava synclines where the directions of paleocurrents have been determinated by classical methods. Results obtained both in Contes and in Peira-Cava on fine-grained detrital beds show a good agreement between directions of paleo-transport deduced from orientation of anisotropy axes and those established by classical methods on the levels showing “sole-marks”. However, in some beds of the Peira-Cava syncline, which are characterized by coarser grain size and “sole-marks” of good quality, the scattering of the directions of the anisotropy axes is very great and in some cases the measurements are not reproducible in the same sample.It appears, therefore, that the measurement of the anisotropy of magnetic susceptibility can constitute a good approach to analysing emplacement modes of fine-grained flysch deposits in which the use of classical methods is often difficult. This method of paleocurrent analysis complements the other techniques used in this field of research. 相似文献