共查询到20条相似文献，搜索用时 31 毫秒
1.
大地电磁三维快速松弛反演并行算法研究(英文) 总被引：8，自引：1，他引：7
为了进一步提高大地电磁三维快速松弛反演的计算效率,在深入分析大地电磁三维快速松弛反演算法的基础上,结合MPI自身的优越性,确定了并行计算的思路,实现了三维快速松弛反演的并行计算。通过理论模型合成数据和实测数据对实现的三维快速松弛反演并行程序进行了试算,分析对比了在多种情况下程序的执行效率。测试结果表明,所实现的三维快速松弛反演并行程序运行结果正确,效率提高明显。此成果在普通微机上实现,推动了大地电磁三维反演技术的实用化,可为其它地球物理三维正反演研究所借鉴。 相似文献
2.
Ahmad Neyamadpour Samsudin Taib W. A. T. Wan Abdullah 《Studia Geophysica et Geodaetica》2009,53(3):389-402
A 3D electrical resistivity imaging survey is presented in this paper. The objective was to investigate an underground wastewater
system at the University of Malaya, Malaysia. Apparent resistivity data were collected along ten parallel lines using a Wenner-Schlumberger
configuration; electrode cables were oriented in the x-direction with 3 m spacing. Roll-along measurements using a line spacing
of 3 m were carried out covering a grid of 20 × 10 electrodes. All data sets were merged into a single data file in order
to perform a 3D inversion. Two different 3D least squares algorithms, based on the robust inversion method and the smoothness-constrained
technique, were used for the inversion of the apparent resistivity data. Both the horizontal and vertical extents of the anomalous
zones found by inversion are displayed. The results indicate the superiority of the robust inversion method over the smoothness-constrained
technique at this site. The results are in sufficient accordance with previously known information about the investigation
area. The results show that 3D electrical resistivity imaging surveys, in combination with an appropriate 3D inversion method,
can be highly useful for engineering and archaeological investigations as well as for environmental applications. 相似文献
3.
To improve the inversion accuracy of time-domain airborne electromagnetic data, we propose a parallel 3D inversion algorithm for airborne EM data based on the direct Gauss–Newton optimization. Forward modeling is performed in the frequency domain based on the scattered secondary electrical field. Then, the inverse Fourier transform and convolution of the transmitting waveform are used to calculate the EM responses and the sensitivity matrix in the time domain for arbitrary transmitting waves. To optimize the computational time and memory requirements, we use the EM “footprint” concept to reduce the model size and obtain the sparse sensitivity matrix. To improve the 3D inversion, we use the OpenMP library and parallel computing. We test the proposed 3D parallel inversion code using two synthetic datasets and a field dataset. The time-domain airborne EM inversion results suggest that the proposed algorithm is effective, efficient, and practical. 相似文献
4.
5.
Photographing layer thicknesses and discontinuities in a marble quarry with 3D GPR visualisation 总被引：1，自引：0，他引：1
An important problem of marble-quarry management is assessing the quality and the homogeneity of quarry blocks before excavation. In this study, we decided to image the limestone, which we studied in a marble quarry, in terms of layer thickness, discontinuities and cavities using the ground-penetrating-radar (GPR) method. The method was successfully applied to detect and map the fractures with the cavities in a marble layer according to depth in the Ankara City Polatli Town (Turkey) region, which represents upper Miocene–Pliocene lacustrine carbonate rocks.This paper is based on interactive transparent 3D visualisation of the 2D GPR profiles to determine changes in layer thickness and discontinuities. In addition, this paper indicates the importance of the appropriate opacity-function construction to obtain transparent 3D visualisation. Firstly we acquired and processed parallel 2D GPR profile data, then we assigned two different amplitude–colour ranges using a limited number of colours to determine the layer thickness and its discontinuities separately. We obtained a 3D volume using parallel 2D GPR data and displayed a limited amplitude range by arranging an opacity function. Therefore, we obtained transparent 3D blocks for thickness and discontinuities, and we formulated an interactive 3D display to image the horizontal, vertical and inclined discontinuities and their directions in the x–y plane versus depth. The GPR results were compared with the petrographical investigation on the basis of textural and mineralogical compositions. The vesicular textures within carbonate platform were supported by the GPR results. 相似文献
6.
基于GPU并行的重力、重力梯度三维正演快速计算及反演策略 总被引：4，自引：2，他引：2
利用NVIDIA CUDA编程平台,实现了基于GPU并行的重力、重力梯度三维快速正演计算方法.采用当前在重力数据约束反演或联合反演中流行的物性模型(密度大小不同、规则排列的长方体单元)作为地下剖分单元,对任意三维复杂模型体均可用很多物性模型进行组合近似,利用解析方法计算出所有物性模型在计算点的异常值并累加求和,得到整个模型体在某一计算点引起的重力(或重力梯度)值.针对精细的复杂模型体产生的问题,采用GPU并行计算技术,主要包括线程有效索引与优化的并行归约技术进行高效计算.在显卡型号为NVIDIA Quadro 2000相对于单线程CPU程序,重力和重力梯度Uxx、Uxy正演计算可以分别达到60与50倍的加速.本文还讨论了GPU并行计算在两种反演方法中的策略,为快速三维反演技术提供了借鉴. 相似文献
7.
大地电磁三维交错网格有限差分数值模拟的并行计算研究 总被引：3，自引：3，他引：0
为了更有效的提高大地电磁三维正演的计算速度,引入了并行处理技术.大地电磁三维交错网格有限差分数值模拟是按照不同频率来计算的,各频率之间求取电磁场值的过程是相互独立的.根据这一特点,可以将多个频率的计算任务平均划分为一个或者几个频率的计算子任务,分配到各个计算节点去并行执行,计算完成后将结果汇总.本文通过采用主从并行模式、分频并行计算的方案,在曙光TC5000A高性能并行平台上实现了基于MPI的大地电磁三维正演的并行计算.通过两个理论模型对实现的大地电磁三维正演并行算法进行试算,对比分析了多个节点机下程序的执行效率.测试结果表明,所实现的三维正演并行算法是正确的、高效的,为进一步的大地电磁三维反演并行算法研究奠定了重要基础. 相似文献
8.
Improved preconditioned conjugate gradient algorithm and application in 3D inversion of gravity-gradiometry data 总被引：1，自引：0，他引：1
With the continuous development of full tensor gradiometer (FTG) measurement techniques, three-dimensional (3D) inversion of FTG data is becoming increasingly used in oil and gas exploration. In the fast processing and interpretation of large-scale high-precision data, the use of the graphics processing unit process unit (GPU) and preconditioning methods are very important in the data inversion. In this paper, an improved preconditioned conjugate gradient algorithm is proposed by combining the symmetric successive over-relaxation (SSOR) technique and the incomplete Choleksy decomposition conjugate gradient algorithm (ICCG). Since preparing the preconditioner requires extra time, a parallel implement based on GPU is proposed. The improved method is then applied in the inversion of noisecontaminated synthetic data to prove its adaptability in the inversion of 3D FTG data. Results show that the parallel SSOR-ICCG algorithm based on NVIDIA Tesla C2050 GPU achieves a speedup of approximately 25 times that of a serial program using a 2.0 GHz Central Processing Unit (CPU). Real airborne gravity-gradiometry data from Vinton salt dome (southwest Louisiana, USA) are also considered. Good results are obtained, which verifies the efficiency and feasibility of the proposed parallel method in fast inversion of 3D FTG data. 相似文献
9.
地震波的正演模拟,尤其是3D正演模拟,往往涉及大规模的数据存储和计算,问题的规模往往超出计算机的物理内存,或者计算时间让问题的求解者难以忍受,即使采用目前存储和计算能力很强的计算机,其计算费用仍然是十分昂贵的.本文提出一种基于多线程协同使用多CPU和计算域分割的正演模拟并行计算技术,使得问题的求解过程得以加快,大大地缩短了用户等待的时间.为了检验我们的并行算法的可行性,文中以傅利叶正演模拟技术为例,给出了声波和3D各向异性弹性波模拟的例子,并对不同版本（串行、并行）运算效率进行了比较,证实了方法的有效性. 相似文献
10.
Ahmad Neyamadpour 《Studia Geophysica et Geodaetica》2011,55(4):755-769
The applicability of three kinds of electrode configurations used to delineate a buried horizontal pipe was studied. A 3D
resistivity imaging survey was carried out along eight parallel lines using pole-pole, pole-dipole, and dipole-dipole arrays
with 1m minimum electrode spacings. Roll-along measurements were carried out to cover a rectangular grid. The 2D and 3D least
squares algorithms based on the robust inversion method were used in the inversion of the apparent resistivity data sets.
The 2D inversion of data sets could not delineate the orientation and dimension of the subsurface anomalies clearly. To obtain
more accurate results, a 3D joint inversion of the pole-pole and pole-dipole data sets was performed, as well as of pole-pole
and dipole-dipole data sets. In this case, both horizontal and vertical dimensions of subsurface structures were resolved.
The resulting model obtained from each array was compared to those of joint inversion method. The result showed that the horizontal
resolution does not improve so much as that in the vertical direction when joint inversion is applied. 相似文献
11.
A 3D model of collected time-domain induced polarization (IP) and electrical resistivity tomography (ERT) data is compiled by geostatistical methods as well as studying spatial correlation among the database. Mesgaran copper deposit, located in Birjand eastern Iran, was chosen to compile and verify the model, leading to five parallel surveyed IP and ERT profiles with dipole–dipole arrays. The collected data were inverted, and then 2D models of IP and ER were prepared; also 3D inversion was done. Afterward, the 3D model has been built by geostatistical methods. Correspondingly, the anomalies threshold was detected by fractal methods and the estimation variance and Kriging efficiency were calculated to validate the modeling. The mineralization zones were determined according to the classified anomalies and those with the lowest error. Results indicated a high correlation between anomalies identified from the model and mineralization. The results made it possible to construct 3D models from surveyed 2D data with acceptable error level. 相似文献
12.
Ahmad Neyamadpour W. A. T. Wan Abdullah Samsudin Taib 《Studia Geophysica et Geodaetica》2010,54(2):299-311
The objective of this paper is to investigate the applicability of four-electrode arrays in 3D electrical resistivity imaging
survey. A 3D resistivity imaging survey was carried out along fourteen parallel lines using dipole-dipole, Wenner-Schlumberger,
and Wenner arrays with 2 m minimum electrode spacings. Roll-along measurements using a line spacing of 1 m were carried out
covering a grid of 20 × 14 electrodes. The 3D least squares algorithm, based on the robust inversion method, was used in the
inversion of the 3D apparent resistivity data sets. The results show that the 3D electrical resistivity imaging survey using
the Wenner-Schlumberger and the dipole-dipole arrays, or the Wenner and the dipole-dipole arrays, in combination with an appropriate
3D inversion method, can be highly useful when the site conditions do not allow using the pole-pole or pole-dipole arrays. 相似文献
13.
2D高密度电法在古墓葬勘探中应用较多,但二维剖面解释局限性愈发突出。以2D平行或等角度放射状测线为基础的拟3D高密度电法能够一定程度上给出三维信息,但对地表条件要求较高,灵活性稍差。3D高密度电法能够给出详细的3D探测信息,但施工效率偏低,且难以适应复杂地表环境。为解决复杂地表环境古墓葬探测问题,提出了一种多方位拟3D高密度电法技术,并在一个位于密集竹林中的大型古墓葬调查中进行了应用研究。结合地表条件布设多个方位的2D高密度电法测线,将多个方位的2D反演数据合并为拟3D数据体,进行可视化解释获得了内部结构的3D信息。结果表明,该技术能够适应复杂环境,拟三维数据不仅能补充二维解释缺失的信息,且与钻探结果基本吻合。 相似文献
14.
各向异性介质对大地电磁观测数据的影响往往不可忽略,因此需要提高大地电磁各向异性三维反演的可靠性和有效性.为了满足大地电磁各向异性三维反演的需求,本文研究了一种基于交叉梯度结构约束的大地电磁主轴各向异性并行三维反演算法.根据大地电磁平面波理论假设,正演方程采用背景场与二次场分离的计算方式,二次场利用交错网格有限差分法求解.由于各向异性反演的多解性,本文将各向异性介质简化为主轴各向异性,并在此基础上进一步采用有限内存拟牛顿LBFGS法实现三维各向异性反演.为了提高各向异性反演的分辨率,反演目标函数中引入交叉梯度项,利用先验的结构信息,对三个方向的电阻率参数进行结构约束,最终的反演进一步利用MPI(Message Passing Interface,消息传递接口)技术实现分频并行计算,测试结果显示并行接近线性加速比. 相似文献
15.
大地电磁三维数据空间反演并行算法研究 总被引：6，自引：4，他引：2
目前大地电磁三维反演实际应用的主要问题是计算效率低.在对大地电磁三维数据空间反演算法进行深入分析的基础上,本文提出了基于频点和矩阵划分的大粒度并行反演方案和具体实现步骤,并在曙光TC5000A高性能计算平台上实现了基于MPI的大地电磁三维数据空间反演并行算法.该算法实现了包括三维正演、灵敏度矩阵、叉积矩阵以及模型改正量的并行执行,不仅计算效率高,而且每个节点机上灵敏度矩阵的存储空间只需原来微机上的2/N(N是参加并行计算的节点机个数),大大地减少了内存开销.通过两个理论模型合成的数据对实现的三维数据空间反演并行算法进行试算,对比分析了多个节点机下程序的执行效率.测试结果表明,所实现的三维数据空间反演并行算法是可行的、高效的,与单机相比,不仅可以提高运行速度,缩短计算时间,而且还可以扩大计算规模,极大地推动了大地电磁三维反演的实用化. 相似文献
16.
17.
Semiautomatic and Automatic Cooperative Inversion of Seismic and Magnetotelluric Data 总被引：1，自引：1，他引：0
Cuong V. A. Le Brett D. Harris Andrew M. Pethick Eric M. Takam Takougang Brendan Howe 《Surveys in Geophysics》2016,37(5):845-896
Natural source electromagnetic methods have the potential to recover rock property distributions from the surface to great depths. Unfortunately, results in complex 3D geo-electrical settings can be disappointing, especially where significant near-surface conductivity variations exist. In such settings, unconstrained inversion of magnetotelluric data is inexorably non-unique. We believe that: (1) correctly introduced information from seismic reflection can substantially improve MT inversion, (2) a cooperative inversion approach can be automated, and (3) massively parallel computing can make such a process viable. Nine inversion strategies including baseline unconstrained inversion and new automated/semiautomated cooperative inversion approaches are applied to industry-scale co-located 3D seismic and magnetotelluric data sets. These data sets were acquired in one of the Carlin gold deposit districts in north-central Nevada, USA. In our approach, seismic information feeds directly into the creation of sets of prior conductivity model and covariance coefficient distributions. We demonstrate how statistical analysis of the distribution of selected seismic attributes can be used to automatically extract subvolumes that form the framework for prior model 3D conductivity distribution. Our cooperative inversion strategies result in detailed subsurface conductivity distributions that are consistent with seismic, electrical logs and geochemical analysis of cores. Such 3D conductivity distributions would be expected to provide clues to 3D velocity structures that could feed back into full seismic inversion for an iterative practical and truly cooperative inversion process. We anticipate that, with the aid of parallel computing, cooperative inversion of seismic and magnetotelluric data can be fully automated, and we hold confidence that significant and practical advances in this direction have been accomplished. 相似文献
18.
《Journal of Applied Geophysics》2008,66(3-4):111-120
Muro Leccese (Lecce) contains one the most important Messapian archaeological sites in southern Italy.The archaeological interest of the site arises from the discovery of the remains of Messapian walls, tombs, roads, etc. (4th–2nd centuries BC) in the neighbourhood. The archaeological remains were found at about 0.3 m depth.At present the site belongs to the municipality, which intends to build a new sewer network through it. The risk of destroying potentially interesting ancient archaeological structures during the works prompted an archaeological survey of the area. The relatively large dimensions of the area (almost 10,000 m2), together with time and cost constraints, made it necessary to use geophysical investigations as a faster means to ascertain the presence of archaeological items. Since the most important targets were expected to be located at a soil depth of about 0.3 m, a ground-penetrating radar (GPR) survey was carried out in an area located near the archaeological excavations. Unfortunately the geological complexity did not allow an easy interpretation of the GPR data.Therefore a 3D electrical resistivity tomography (ERT) scan was conducted in order to resolve these interpretation problems.A three-way comparison of the results of the dense ERT measurements parallel to the x axis, the results of the measurements parallel to the y axis and the combined results was performed.Subsequently the synthetic model approach was used to provide a better characterization of the resistivity anomalies visible on the ERT field data.The 3D inversion results clearly illustrate the capability to resolve in view of quality 3D structures of archaeological interest. According to the presented data the inversion models along one direction (x or y) seems to be adequate in reconstructing the subsurface structures.Naturally field data produce good quality reconstructions of the archaeological features only if the x-line and y-line measurements are considered together. Despite the increased computational time required by the 3D acquisition and 3D inversion schemes, good quality results can be produced. 相似文献
19.
为适应实际生产中对大规模三维工区数据处理的效果及效率的要求,提出了按三维成像体输出成像结果的3D Kirchhoff积分法偏移实现方案.将地震数据按共偏移距道集形式排放,每个共偏移距数据的偏移类似于一个3D叠后Kirchhoff积分偏移,极大地降低了对计算机内存和局部盘及I/O通讯率的要求.每个地震道的成像(输出等时面)在由炮检点连线定义的旋转坐标系中进行,更好地考虑了偏移孔径计算及反假频处理.同时兼顾了超大规模地震数据PSTM成像处理中内存需求量、I/O通讯问题、并行处理方案及效率优化的细节问题.并行计算用偏移距号和每个共偏移距数据体中的线号作为一级和二级索引进行任务分解,更适应当前计算机集群中计算节点比较多的情况.最后考虑了在基本不影响效率的前提下的断点保护处理方案.理论及实际数据测试结果说明了该方案的可行性,与商业软件的对比验证了该方案的优越性.在此较完善的实现方案基础上,可以容易地把更优越的积分类偏移方法迅速推向实用化. 相似文献
20.
基于交错网格伪谱法和高阶精度有限差分方法,发展了模拟非均匀介质地震波传播的三维伪谱和有限差分混合算法.该方法在两个水平方向利用交错网格伪谱算子计算空间微分,保留了该方法高效、高精度的优势,在垂直方向采用交错网格高阶精度有限差分算子实现空间微分计算．利用有限差分方法的局部性特征,将三维计算区域在垂直方向上划分为一系列子区域,并分配给不同的处理器,实现了在并行计算机集群上的三维并行计算．通过模拟算例,与离散波数法比较,检验了该算法的精度．为了检验该方法的实用性,在64个处理器上,对三维沉积盆地模型进行了67108864个网格点的并行计算,模拟的波场主频率为1.25Hz,讨论了沉积盆地深度对三维沉积盆地地面运动的影响． 相似文献