Statistical fusion of two-scale images of porous media

The reconstruction of the architecture of void space in porous media is a challenging task, since porous media contain pore structures at multiple scales. Whereas past methods have been limited to producing samples with matching statistical behavior, the patterns of grey-level values in a measured sample actually say something about the unresolved details, thus we propose a statistical fusion framework for reconstructing high-resolution porous media images from low-resolution measurements. The proposed framework is based on a posterior sampling approach in which information obtained by low-resolution (MRI or X-ray) measurements is combined with prior models inferred from high-resolution microscopic data, typically 2D. In this paper, we focus on two-scale reconstruction tasks in which the measurements resolve only the large scale structures, leaving the small-scale to be inferred. The evaluation of the results generated by the proposed method shows the strong ability of the proposed method in reconstructing fine-scale structures positively correlated with the underlying ground truth. Comparing our method with the recent method of Okabe and Blunt [12], in which the measurements are also used in the reconstruction, we conclude that our method is more robust to the resolution of the measurement, and more closely matches the underlying fine-scale field.     

嘉峪关地电场观测资料分析

研究了大地电场变化的基本要素,对嘉峪关地电场观测资料的质量进行了评价和分析,得到:嘉峪关台地电场观测基本反映了地电场的真实变化,特别对大地电场变化的记录准确.并研究了嘉峪关台附近及周围发生的4次中强地震前地电场、大地电场短临前兆现象,认为震前都显示了一定的短临异常.     

重力和重力梯度数据三维相关成像

本文提出了重力异常三维相关成像方法和重力梯度数据三维相关成像方法,并提出了基于异常分离的三维相关成像方法来提高成像分辨率.通过合成Y型岩脉模型和合成多个直立长方体组合模型的重力异常和重力梯度数据试验分析,验证了本文三维相关成像方法可显示出异常地质体的空间赋存状态和等效剩余质量分布,具有良好的纵向和横向分辨率.     

成像测井新技术在水利工程中的应用

工程钻孔成像测井仪可以在工程勘察孔中进行全孔声时、声幅和视频成像,成像测井结果采用展开式钻孔柱状成图方式表示,直观形象,便于分析.钻孔成像测井技术在油气勘探中已经发挥了重要的作用,然而在工程中的应用尚处在探索阶段.本文简要介绍了RG型成像测井系统的构成和测试工作原理,并介绍了该套成像测井系统在水工大坝、混凝土防渗墙等水利工程钻孔测试中的应用效果.     

田野白蚁主巢的高密度电法探测实例

白蚁个体虽小,其危害却几乎涉及到国民经济的各个领域,对房屋建筑、水库堤坝、山林果园、通讯设备等的危害尤为严重.根据白蚁蚁巢的特点,应用地球物理探测技术来探寻蚁巢的位置,从理论上讲是完全可行的,在实际的应用上也有很好的效果,而且是一种新的探寻白蚁蚁巢的有效方法.     

星载SAR成像参数联合估计方法

通信系统的不可靠性会造成SAR卫星下发数据出现误码或丢失,从而导致几何参数的解译、计算出现较大的误差或者缺失,限制了SAR数据成像处理及后续利用。针对该问题,提出一种基于回波数据的成像参数联合估计方法。首先通过回波数据进行多普勒中心频率估计和多普勒调频斜率估计;然后,根据SAR多普勒参数特性,建立多普勒参数与几何参数之间的超定方程组,并利用多普勒参数估计值求解方程组反演几何参数;最后,利用多普勒参数估计值和几何参数估计值完成SAR数据成像处理。实验结果表明,本文方法可以获得可靠的多普勒参数估计值和几何参数估计值,从而有效地解决像参数欠缺情况下的星载SAR成像处理问题。     

Study on 3D simulation of wave fields in acoustic reflection image logging

The borehole acoustic reflection imaging logging is a newly developed acoustic logging method that has attracted many interests. These converted and reflected waves for imaging are usually mixed up with borehole guided waves and therefore difficult to be clearly identified. To improve the downhole tool design and develop more sophisticate data processing and interpretation algorithms,studies on precisely numerical modeling of the wave fields in the acoustic reflection imaging logging are neces-sary and critical. This paper developed a parallelized scheme of 3D finite difference (3DFD) with non-uniform staggered grid and PML absorbing boundary to simulate the acoustic wave fields in isotropic and anisotropic formations. Applications of this scheme to the typical cases of isotropic and anisot-ropic formations and comparison with the results from published analytical solutions have demon-strated the validation and efficiency of the scheme. Higher accuracy and lower computation cost (3.5 times faster than the conventional schemes) have been achieved with this scheme for modeling such a complex wave fields of 60 dB dynamic range with higher frequency (10 kHz). This simulating program provides a quantitative analytical means for studying acoustic reflection imaging tool and development of the data processing and interpretation methods.     

A new family of non-linear filters for background subtraction of wide-field surveys

In this paper the definitions and properties of a newly dedicated set of high-frequency filters based on smoothing-and-clipping are briefly described. New applications for the reduction of wide-field 2048x2048 CCD spectral and direct images of a new deep survey KISS are also presented.     

GPR velocity determination by image-wave remigration

We have studied in detail the theoretical and numerical properties of a finite-difference algorithm for image-wave time-remigration. For a number of synthetic models, numerical experiments have been performed. For these examples, we obtained perfect agreement between the theoretical predictions and numerical results. The examples also prove the computational efficiency of the algorithm. An application to ground-penetrating-radar (GPR) data demonstrates that image-wave remigration can be used to estimate models with laterally varying velocities. The quality of the latter is confirmed by a final zero-offset time migration.     

Surface velocity network with anti-solar differential rotation on the activeK-giant σ Geminorum

We demonstrate the power of the local correlation tracking technique on stellar data for the first time. We recover the spot migration pattern of the long-period RS CVn-type binary σ Gem from a set of six Doppler images from 3.6 consecutive rotation cycles. The resulting surface flow map suggests a weak anti-solar differential rotation with α ≈ –0.0022 ± 0.0016, and a coherent poleward spot migration with an average velocity of 220 ± 10ms-1. This result agrees with our recent findings from another study and could also be confirmed theoretically. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)