共查询到20条相似文献，搜索用时 31 毫秒
1.
位场全张量梯度数据以其信息量大、含有更高频的信号成分,能更好地描述小的异常特征等优点在地球物理领域中得到广泛应用.边界检测是位场解释中不可缺少的任务,需要新的边界探测器来处理位场梯度张量数据.为了充分利用位场梯度张量数据的多信息成分,本文定义了方向总水平导数和加强方向总水平导数,并利用其定义新的边界检测器.为了能同时显示不同振幅大小异常的边界,本文对其进行了归一化处理.通过模型试验,证明了归一化方法能更加清晰准确地显示浅部和深部的地质体边界信息.最后将该边界检测方法用于加拿大圣乔治湾实际测得全张量重力梯度数据和中国朱日和地区的磁异常数据中,并得到了较好的边界检测结果. 相似文献
2.
Recently, Normalized Full Gradient (NFG) method has widespread applications to natural potential fields, especially in gravity and magnetic. In this study, usage of NFG in Self-Potential (SP) data evaluation is tested. Results are compared to other SP interpretation methods. The NFG method is applied to synthetic and field SP data. As a consequence of application of the method to the anomalies of spherical, cylindrical and vertical sheet models, whose theoretical structures are explicit, the structures were found very close to their actual locations. In order to see the capability of the method in detecting the number of sources, NFG method was applied to different spherical models at different depths and locations. The least-squares inverse solution was applied to the same models and NFG method was found more powerful in detecting model structure. Sensitivity of NFG method for application to noisy data is also tested. An anomaly is generated by adding a random noise to two close sphere SP anomalies. The method seems to work for the two close spheres at high S/N ratio. Then, NFG method was applied to two field examples. The first one is the cross section taken from the SP anomaly map of the Ergani-Süleymanköy (Turkey) copper mine. The depth of the mineral deposit at that site was found about 38 m from the ground level. This result is well matched to previous studies. NFG was also applied to SP data from Seferihisar Izmir (Western Turkey) geothermal field and the location of the point source was determined. The field data of this site have already been modeled by the thermoelectric source (coupling) solution method. When these two methods are compared, they seem to support each other. It is concluded that the NFG method works perfectly when the structure model is simple. It is observed that natural potential sources close to earth’s surface are identified by the method more accurately at greater harmonics, while deep sources are identified at lesser harmonics. It produces reasonable results for noisy multi-source models than the other parameter identification methods (inverse solution, power spectrum, etc.). 相似文献
3.
A general step-by-step solution technique is presented for the evaluation of the dynamic response of structural systems with physical and geometrical nonlinearities. The algorithm is stable for all time increments and in the analysis of linear systems introduces a predictable amount of error for a specified time step. Guidelines are given for the selection of the time step size for different types of dynamic loadings. The method can be applied to the static and dynamic analysis of both discrete structural systems and continuous solids idealized as an assemblage of finite elements. Results of several nonlinear analyses are presented and compared with results obtained by other methods and from experiments. 相似文献
4.
奇异谱分析是一种近年兴起的时间序列分析方法,它利用降秩原理实现信号分离.该方法将数据空间投影到不同特征的子空间中,并用奇异值来表征这些子空间的性质,最后通过截取奇异值实现数据的重构.重磁位场分离可以看成一种多信号叠加的分离问题.不同特征的重磁异常具有不同特征的奇异谱,这是奇异谱分析用于解决位场分离问题的应用基础.本文通过建立理论模型,分析重磁异常的奇异谱特征,得出适用于重磁位场分离的最优参数选择方法,并与传统方法进行比较.对比发现,无论是横向叠加模型、垂向叠加模型还是斜向叠加模型,奇异谱分析都具有很好的分离效果.最后,将奇异谱分析用于鄂东南某矿区的重力资料处理中,实现弱异常的识别和分离. 相似文献
5.
Buddhadeb Banerjee 《Pure and Applied Geophysics》1970,82(1):238-250
Summary Quantitative interpretation of SP anomalies due to vertical and nearly vertical, thin sheets of infinite horizontal extension has been developed in this paper. The methods proposed utilise selective SP values at some selected points on the profile thus enabling us to get the different parameters of the causative body directly. Also, for the case of vertical sheet, an interpretation technique has been formulated when the base station is within the zone of influence of the potential field of the causative body. 相似文献
6.
在矿井瞬变电磁超前探测数据处理和解释中,为了更好地识别巷道前方含水体电性分界面,利用扩散场与波动场间的函数关系,将矿井瞬变电磁法超前探测中瞬变电磁波场转换为拟地震波场,实现波场转换.同时,为了解决波场转换后信号幅值偏弱,以增加信噪比利于解释,利用雷达的合成孔径方法对波场转换后的拟地震信号进行相关叠加处理.将矿井瞬变电磁法巷道超前探测的同一测点不同探测方向的数据作为孔径数据进行合成孔径成像,以突出弱异常而提高信噪比,结合应用实例验证了方法的效果.研究表明,矿井瞬变电磁法合成孔径成像方法能够提高电性界面信息的信噪比和界面几何分辨率,对矿井瞬变电磁法精细超前探测含水构造具有重要的理论意义和应用价值. 相似文献
7.
Ralph R.B. Von Frese William J. Hinze Lawrence W. Braile 《Earth and Planetary Science Letters》1981,53(1):69-83
To facilitate geologic interpretation of satellite elevation potential field data, analysis techniques are developed and verified in the spherical domain that are commensurate with conventional flat earth methods of potential field interpretation. A powerful approach to the spherical earth problem relates potential field anomalies to a distribution of equivalent point sources by least squares matrix inversion. Linear transformations of the equivalent source field lead to corresponding geoidal anomalies, pseudo-anomalies, vector anomaly components, spatial derivatives, continuations, and differential magnetic pole reductions. A number of examples using 1°-averaged surface free-air gravity anomalies and POGO satellite magnetometer data for the United States, Mexico and Central America illustrate the capabilities of the method. 相似文献
8.
B. S. R. Rao I. V. Radhakrishna Murthy S. Jeevananda Reddy 《Pure and Applied Geophysics》1970,78(1):66-77
Summary An entirely new procedure for interpreting selfpotential anomalies of spheres, rods and dipping sheets is presented. The anomaly of a sphere is divided into two parts — the anomaly of odd symmetry and the anomaly of even symmetry — from which the depth can be obtained by fitting them with the master curves. The self-potential anomalies of a finite rod are transformed to the anomalies of a veritcal sheet, for which standard curves are presented. The case of a sheet was divided into three parts; (a) finite line of poles; (b) infinite double line of poles and (c) finite double line of poles. For the first case logarithmic curves were prepared and presented; by their comparison with the field profile, different parameters can be obtained. In the second case, a geometrical construction is provided to obtain the various values. In the third case, the anomalies of finite sheet (finite double line of poles) are transformed into those due to an infinite double line of poles for interpretation. 相似文献
9.
基于重力异常分离方法寻找深部隐伏铁矿 ——以安徽泥河铁矿为例 总被引：5，自引：4，他引：1
重力异常是地下不同规模、不同形态和不同埋深的不均匀地质体的综合响应,重力勘探主要通过从重力异常中提取感兴趣的局部异常,以便探测深部结构,寻找隐伏矿床.为探讨重力异常分离原则并检验方法效果,本文从各方法原理入手,加上模型试验以及在安徽省泥河矿区深部隐伏铁矿的探寻实践检验,阐明:趋势分析法是整体拟合不同于最小二乘圆滑的局部拟合,由于是多项式拟合区域场,趋势分析法不适宜范围大、地质情况复杂的测区;插值切割法以计算点场值与四点圆周平均值的插值运算为切割算子,通过连续切割,得到重力异常的切割区域场和局部场,插值切割法对于小测区单个异常的分离效果较好,切割次数选择1到2次即可;匹配滤波法通过分析实测异常功率谱曲线、选择合适的滤波段、建造适宜的低通和带通滤波器进行滤波,从而提取不同波数成分的异常场,匹配滤波更适合垂向叠加的异常分离;解析延拓是根据一个面上的一组位场数据确定另一个不同高度面上位场值,应用中要把握延拓高度;垂向二阶导数法可以起到突出浅源异常,区分水平叠加异常,确定异常体的边界,消除或削弱背景场的作用.通过安徽泥河铁矿重力异常分离实验,发现三阶趋势分析、向上延拓以及插值切割法能很好地分离出矿体异常和背景场,同时发现在泥河矿区东南部和东北部还存在剩余重力异常,可为泥河铁矿扩大规模提供新的线索. 相似文献
10.
Georgios Panou Nikos Yannakakis Demitris Delikaraoglou 《Studia Geophysica et Geodaetica》2013,57(2):203-216
In this paper the linear fixed altimetry-gravimetry boundary-value problem is analyzed with respect to the existence and uniqueness of the solution. Nowadays, it is possible to determine very precisely points on the physical surface of the Earth by 3D satellite positioning and the problem is to determine the disturbing potential in an unbounded domain representing the exterior of the Earth. In order to establish realistic boundary conditions, a Dirichlet condition is imposed at seas and an oblique derivative condition on land. Then, mathematical methods are used within the frame of functional analysis for attacking the problem under consideration. Specifically, the Stampacchia theorem is used to decide upon the existence and uniqueness of the weak solution of the problem in a weighted Sobolev space. Finally, we confirm that the condition of validity for such a theorem has a geometrical interpretation. 相似文献
11.
Mansour A. Al-Garni 《Acta Geophysica》2010,58(1):143-162
A new approach is proposed in order to interpret spontaneous potential (self-potential) anomalies related to simple geometric-shaped
models such as sphere, horizontal cylinder, and vertical cylinder. This approach is mainly based on using neural network inversion
of SP anomalies, particularly modular algorithm, for estimating the parameters of different simple geometrical bodies. However,
Hilbert transforms are involved to determine the origin location in order to reduce the parameters which minimize the ambiguity
in the inverted models. The inversion has been tested first on synthetic data from different models, using only one well-trained
network. The results of inversion show that the parameter values derived by the inversion are identical to the true values
of parameters. Noise analysis has been also examined, where the results of the inversion produce acceptable results up to
10% of white Gaussian noise. The validity of the neural network inversion is demonstrated through published real field SP
taken from southern Bavarian Woods, Germany. A comparable and acceptable agreement is shown between the results of inversion
derived by the neural network and those from the real field data. 相似文献
12.
化向地磁极(化极)是最基本的磁测资料处理方法之一,化极能消除或减少斜磁化影响,提高对磁测资料的认识程度和解释水平,对研究地壳产生的磁异常具有重要意义.但低纬度地区特别是磁赤道处,化极处理很不稳定甚至奇异,一直是位场研究的难点.针对地磁纬度较低特别是磁赤道地区磁异常化极的困难,利用从磁北极处垂直磁化向低纬度地区水平磁化方向转换稳定的特点,提出"狭义化赤"概念,并将其与低纬度磁异常"倒相"解释方法结合,提出专门用于磁赤道处化极的方法.该方法扩展了现有的化极理论,实现了磁赤道处的稳定化极.区别于目前任何方法,专门用于(近)水平磁化条件下的化极计算,具有原理简单,实现方便,收敛速度快等特点.对理论模型和实际资料计算表明这种针对磁赤道地区磁异常的化极处理方法是稳定、可靠的. 相似文献
13.
We have developed a least-squares minimization approach to determine the depth and the amplitude coefficient of a buried structure
from residual gravity anomaly profile. This approach is basically based on application of Werner deconvolution method to gravity
formulas due to spheres and cylinders, and solving a set of algebraic linear equations to estimate the two-model parameters.
The validity of this new method is demonstrated through studying and analyzing two synthetic gravity anomalies, using simulated
data generated from a known model with different random error components and a known statistical distribution. After being
theoretically proven, this approach was applied on two real field gravity anomalies from Cuba and Sweden. The agreement between
the results obtained by the proposed method and those obtained by other interpretation methods is good and comparable. Moreover,
the depth obtained by the proposed approach is found to be in very good agreement with that obtained from drilling information. 相似文献
14.
The theory of physical interaction field by a differential geometrical approach combines the deformation field with the physical field (e.g., electromagnetic field), and derives a new tensorial relation between the deformation and the dielectric anisotropy of the crustal rocks. This relation can be applied to dielectric anisotropies of deformed natural rocks such as mylonites or gneisses. The dielectric anisotropies of mylonites are observed to increase as plastic strains of mylonites increase. Moreover, the derived tensorial relation can be linked to the electromagnetic potential field (deformational anomalies) in a deformed crust. A physico-geometrical consideration on this theory of physical interaction field is mathematically similar to ones on the theory of field in the Finsler space or on the concept of a unified gauge field. 相似文献
15.
A comprehensive numerical analysis of the seismic response and site period of curved alluvial valleys was performed by taking into account the characteristics of sedimentary materials. This study presents a criterion as a combination of the three following geometrical and geotechnical characteristics of curved valleys in order to provide a simple method for code implementation of complex site effects: depth ratio, filling ratio and impedance ratio. The parametric studies were performed by a HYBRID program combining finite elements in the near field and boundary elements in the far field (FEM/BEM). The amplification patterns under above-mentioned characteristics were determined at the central point of valleys. The results are shown in the form of response spectra. Different impedance coefficients of materials were considered to evaluate effects resulting from combination with filling ratio and geometrical parameters. Finally, a criterion is proposed in terms of engineering applications to assess the spectral response at the surface of curved alluvial valleys. 相似文献
16.
The guaranteed approach to the solution of inverse problems of gravimetry, which is fundamentally different from the common solution, is presented. Instead of providing single (optimum) estimates of the model parameters, whose quality is, generally, random, the interpretation in the suggested approach yields that volume of reliable information on disturbing objects, which is contained in the field measurements, together with the a priori constraints. The method of solving the inverse problem of gravimetry is developed within this approach, where, in contrast to the conventional approach, both the geometrical parameters of the geological bodies and the densities of their composing rocks are treated as unknowns. The generalized assembly algorithm suggested by V.N. Strakhov is proposed as a basic working tool to implement this approach. The results of testing this algorithm and the guaranteed approach itself on the model and practical examples are discussed. 相似文献
17.
边界识别技术是位场数据解释中一项基本的工作,现有的边界识别方法多存在边界识别结果发散和不能均衡深浅地质体异常的缺点.目前一些均衡边界识别方法会因正负异常同时存在而引起额外的错误边界或者存在人为主观因素去除错误边界信息的缺点.本文充分利用重力位场张量梯度的多信息成分,提出利用水平方向解析信号及其垂向导数与传统的均衡边界识别方法做结合的方式定义新的探测边界的方法.通过理论模型试验证明新方法同传统方法相比,能够更加清晰、准确的圈定出深浅地质体的边界.最后将新的边界识别方法应用到实测重力异常数据解释中,取得了良好的边界识别结果并能够发现更多的构造细节. 相似文献
18.
This study integrates potential gravity and magnetic field data with remotely sensed images and geological data in an effort to understand the subsurface major geological structures in Afghanistan. Integrated analysis of Landsat SRTM data was applied for extraction of geological lineaments. The potential field data were analyzed using gradient interpretation techniques, such as analytic signal (AS), tilt derivative (TDR), horizontal gradient of the tilt derivative (HG-TDR), Euler Deconvolution (ED) and power spectrum methods, and results were correlated with known geological structures.The analysis of remote sensing data and potential field data reveals the regional geological structural characteristics of Afghanistan. The power spectrum analysis of magnetic and gravity data suggests shallow basement rocks at around 1 to 1.5 km depth. The results of TDR of potential field data are in agreement with the location of the major regional fault structures and also the location of the basins and swells, except in the Helmand region (SW Afghanistan) where many high potential field anomalies are observed and attributed to batholiths and near-surface volcanic rocks intrusions.A high-resolution airborne geophysical survey in the data sparse region of eastern Afghanistan is recommended in order to have a complete image of the potential field anomalies. 相似文献
19.
人工源宽角反射(折射)地震资料具有偏移距较大、信噪比较低等特点,通常用于地震波走时反演重建地壳速度结构。逆时偏移成像方法作为勘探地震学领域获取地下构造形态的有效手段之一,可以有效弥补走时反演方法的不足。本文针对大偏移距宽角反射(折射)地震实验,利用四边形网格谱元法进行波场模拟,结合了有限元法的灵活性和谱方法的指数收敛性,高效且高精度获取模型合成地震记录,后采用逆时偏移成像方法将合成地震记录偏移归位,获取地壳几何结构,验证了逆时偏移成像方法在宽角地震资料处理及结果解释中的适用性,为后期实际地震资料的偏移成像提供了理论依据和支持。 相似文献
20.
常规欧拉反褶积法中构造指数的选取以及分散解存在较多的问题,提出了基于联立垂向一阶导数与解析信号的欧拉齐次方程的RDAS-Euler反演方法。该方法可以更为精确的估计场源的范围及埋深,且不需考虑构造指数N的影响,避免了因构造指数不当而引起的反演误差。通过对单一地质体及组合地质体模型的实验证明本文方法能有效地完成目标体的反演工作,反演结果与理论值之间的误差小于10%,且相对于常规欧拉反褶积法更加稳定准确,能够更好的得到地质体边界及深度信息。将RDAS-Euler法应用于黑龙江省虎林盆地实测布格重力异常数据,获得了丰富的断裂信息,说明RDASEuler法增强了对断裂平面位置的识别能力。 相似文献