Broadband synthetic aperture borehole radar interferometry   总被引：1，自引：0，他引：1  

I. Mason  N. Osman  Q. Liu  C. Simmat  M. Li 《Journal of Applied Geophysics》2001,47(3-4)

Trials in mines have established that wideband VHF borehole radars (BHR), working in the 10–100-MHz band, can be used to probe the rockmass between boreholes over ranges from <5 m to as much as 150 m with submeter resolution. There is evidence that ore bodies reflect these radar signals both specularly and diffusely, much as the ground/air interface does when overflown by synthetic aperture radar (SAR). In both SAR and BHR, multiple flight lines, together with diffuse reflections admit the possibility of developing interferometric 3D images of the object. This paper examines the possibility of imaging buried objects in three dimensions by interferometrically combining broadband VHF borehole radar profiles shot in adjacent pairs of boreholes. Broadbanding in BHR has the advantage of releasing the image from 2nπ phase ambiguities, but practically, interferometric borehole radar (InBHR) needs high signal-to-noise ratios (SNR) to avoid noise capture. This means that 3D InBHR is limited to ranges in wavelengths which are less than the rock's attenuation factor Q. Interferometric methods are developed which are capable of mapping ore bodies and other structures in three dimensions. Tangent plane migration methods are developed here in order to reconstruct surfaces that lie in the near-field of sparse interferometric arrays.  相似文献   

钻孔应变,应力测量区域特征初探   总被引：1，自引：0，他引：1  

赵淑平 《地震研究》1992,15(3):283-290

我国钻孔应变、应力测量依不同时段区域变化形态有明显差异;短期(一月内)、中期(一年内)区域变化特征不显著。正常形态显示平稳、应变测量显示固体潮形态、应力测量显示年变形态。震前异常多呈现突升、突降式的应变阶跃、固体潮畸变、年变形态改变。长期(10年内)与其构造部位、地震活动性及区域构造运动,矢量速率有一定的相关性,因而存在着明显的区域变化特征。识别不同区域的曲线变化特征,对判定震兆信息有一定的指导作用,从而提高了应变、应力测量资料的应用价值。  相似文献   

Wide-Field Camera for Gravitational Microlensing Survey: MOA-cam2     

Toshifumi Yanagisawa  Yasushi Muraki  Yutaka Matsubara  Fumio Abe  Kimiaki Masuda  Sachiyo Noda  Takahiro Sumi  Yuji Kato  Mitsuaki Fujimoto  Shuji Sato  Ian Bond  Nicholas Rattenbury  Philip Yock  Pam Kilmartin  John Hearnshaw  Micheal Reid  Denis Sullivan  Brian Carter  Richard Dodd  Garry Nankivell  Noiman Rumsey  Morihiro Honda  Maki Sekiguchi  Masanori Yoshizawa  Takashi Nakamura  Humitaka Sato  Seiji Kabe  Makoto Kobayashi  Yoshiyuki Watase  Jun Jugaku  Toshiharu Saito  Barbel Koribalsky 《Experimental Astronomy》2000,10(4):519-535

We have constructed a large, mosaic CCD camera called MOA-cam2 which has 4096 × 6144-pixelsto search for gravitational microlensing events. MOA-cam2 has three4096 × 2048-pixel SITe CCD chips, which have a very high quantum efficiency (nearly 80% in the wave region 500 to 800 nm),and three buttable sides. We have placed the threechips side by side with 100 m dead space. MOA-cam2 has been installed on the 61 cm Boller and Chivens telescope of the MOA collaboration at the Mt. John University Observatory (MJUO) in NewZealand since July 1998. The field coverage is 0.92° × 1.38° per exposure. The technical details of MOA-cam2 and the first images obtained with the Boller and Chivens telescope are presented. MOA-cam2 introduces a second phase of research on gravitational microlensing by the MOA collaboration.  相似文献   

数字近景摄影测量测图应用探讨   总被引：8，自引：2，他引：8  

张建霞  王留召  王宝山 《测绘科学》2006,31(2):47-48

非量测性的数码相机已成为摄影测量中应用研究的热点。论文阐述了利用大面阵数码相机实现近景摄影测量测图的理论、方法与步骤,并通过具体试验加以验证。试验结果表明,基于大面阵相机的近景摄影测量能满足大比例尺测图精度要求。  相似文献   

一种根据曲率变化检校畸变差的方法     

康志忠  谭玉敏 《武汉大学学报(信息科学版)》2006,31(9):777-780

提出了基于曲率变化的畸变差检校方法。首先对影像上提取的直线进行二分，根据重新匹配出的直线可确定实际物方直线在影像上的投影因镜头畸变而产生弯曲的程度，以此可对镜头的畸变进行检校。但对于镜头畸变较大的情况二分直线无法检测出实际曲线的弯曲程度，因此，需要对所有共线的直线进行分组，由每组直线来确定实际曲线的弯曲程度，检校镜头畸变，从而消除其对影像的影响。实验证明，通过这种方法对镜头畸变进行检校，能够得到较好的结果。  相似文献   

Effect of fluid pressure on rock compressive failure in a nearly impermeable crystalline rock: Implication on mechanism of borehole breakouts   总被引：1，自引：0，他引：1  

Chandong Chang  Bezalel Haimson 《Engineering Geology》2007,89(3-4):230-242

We conducted laboratory true triaxial experiments in the nearly impermeable Pohang rhyolite to investigate failure mechanisms under ‘dry’ and ‘wet’ rock conditions. Under ‘dry’ conditions prismatic specimens were jacketed all around to prevent confining fluid penetration. Under ‘wet’ conditions one pair of the specimen faces was left unjacketed and in direct contact with the confining fluid (kerosene) applying the least principal stress in an attempt to simulate the case of an unlined borehole wall. In both testing setups the true triaxial compressive strength for a given least principal stress increases significantly as the intermediate principal stress rises. The unjacketed rhyolite strength is, however, only 60 to 85% of the strength under dry conditions, depending on the magnitude of the intermediate principal stress. In dry rhyolite the failure process begins upon dilatancy onset, followed by microcrack localization, and ending in a steeply dipping shear fracture. On the other hand, brittle fracture in wet specimens occurs almost immediately after the onset of dilatancy by the development of one or more through-going extensile fractures subparallel and adjacent to one of the unjacketed faces, resembling the extensile cracks leading to borehole breakouts in crystalline rocks. We infer that upon dilatancy the confining fluid intrudes and quickly propagates newly opened stress-induced microcracks subparallel to the unjacketed faces, leading to ‘early’ failure.  相似文献   

Development of a practical photogrammetric network design using evolutionary computing     

Gustavo  Olague Enrique  Dunn 《The Photogrammetric Record》2007,22(117):22-38

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A review and analyses of plumb-line calibration     

José L.  Lerma  Miriam  Cabrelles 《The Photogrammetric Record》2007,22(118):135-150

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多尺度的DMC彩色合成影像辐射再处理方法     

潘俊  王密 《武汉大学学报(信息科学版)》2007,32(9):800-803

在分析DMC（digital mapping camera）彩色合成影像存在的色彩过渡不平滑现象的特点和成因的基础上,提出了一种多尺度辐射再处理方法来改善影像质量。该方法采用多尺度处理策略,能自动定位拼接线和过渡区域的具体位置。实验表明,本文方法能够有效地改善DMC彩色合成影像的质量。  相似文献   

关于数字航测相机像移补偿问题   总被引：3，自引：0，他引：3  

常本义 《测绘学院学报》1998,(2)

航测相机像移补偿有两种方法 :一是在相机的焦平面上 ,使感光平面沿飞行方向 ,在曝光瞬间作一微小位移 ,以改正因摄影平台相对于被摄目标的运动引起的像点位移 ;二是在曝光瞬间 ,使相机作一微小的俯仰角旋转 ,以改正因摄影平台相对于被摄目标的运动引起的像点位移。前者简称为焦平面平移改正法 ,后者可称为俯仰旋转改正法。本文中研究了这两种像移补偿方法的差异和所能达到的精度水平及其适用范围  相似文献