Broadband synthetic aperture borehole radar interferometry

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.     

X-Ray Interferometry

For the astronomer, X-ray interferometry is the theory and practice of building dilute aperture telescopes for studying celestial X-ray sources. The short wavelengths and high surface brightness of X-ray sources will make the eventual scientific payoff very high, with direct imaging of the event horizons of black holes as the centerpiece. In this article, we review the history of X-ray interferometry and discuss the recent technical developments toward astronomical applications. We present several mission concepts and show they are achievable with todays technology.     

中国隧道及井巷地震波法超前探测技术研究分析

自20世纪90年代以来，反射地震波法作为一种主要的超前探测技术在我国国内隧道及井巷工程中取得了诸多成功应用的探测实例，同时在应用中不同探测方法也存在不少问题。文章结合国内外超前探测中应用较为广泛的TSP法、负视速度法、HSP法、TRT法、ISIS系统等反射波探测技术加以阐明，分析了国内超前探测技术应用与研究的现状，指出隧道及井巷超前探测数据采集与处理过程中存在的不足，并进一步提出超前探测研究在正反演理论、数据采集、偏移成像技术等方面应该注意的问题，超前探测的目标是要建立和完善一套实时的巷道前方地质体的动态监测与预报系统。     

EH-4电导率成像系统的特点及其在金属矿勘探中的应用

EH-4电导率成像系统是一种混场源频率域电磁观测系统,具有轻便、高效、勘探深度大、分辨率高的特点。通过在块状硫化物铜矿、斑岩铜矿已知矿区的试验研究,证实EH-4系统在这两种矿床类型的隐伏-半隐伏金属矿勘探中有较好的找矿效果。     

成像光谱技术在典型蚀变矿物识别和填图中的应用

成像光谱矿物识别和填图技术是中国国土资源调查和监测重点发展的高新技术之一。笔者以国土资源调查应用为主要目标,研究了成像光谱矿物识别和矿物填图技术实用化中的一些关键技术问题。分析了白云母和绿泥石两种重要蚀变矿物的光谱特征及光谱变异特征;以新疆东天山黄山地区的HyMap数据为例,对目前已较为系统化的成像光谱识别技术(如MNF变换、像元纯度指数PPI和N维可视化端元识别NDVI)在典型蚀变矿物识别和填图中的应用进行介绍。     

成像光谱数据特征选择及小麦品种识别实验研究

针对河北栾城获得的MAIS成像光谱仪数据用于小麦品种识别进行了特征选择和分类研究。利用遗传算法以JM距离为准则并结合实验区小麦的生物物理特性，进行了最佳波段选择；利用Fuzzy—Anmap分类器及选出的最佳波段对成像光谱数据进行了分类，区分出了4种小麦品种，小麦的总体分类精度超过97％。     

云南思茅—中甸地震剖面的地壳结构

云南思茅—中甸宽角反射/折射地震剖面切割松潘—甘孜、扬子和华南三个构造单元的部分区域. 我们利用初至波和壳内反射波走时层析成像获得地壳纵波速度结构. 在获得新的地壳速度结构模型基础上，利用地震散射成像思想和低叠加次数的叠前深度偏移方法重建了研究区的地壳、上地幔反射结构. 综合分析研究区地壳P波速度模型和壳内地震反射剖面发现：沿测线从北至南地壳厚度从约50 km减薄至35 km左右，地壳厚度的减薄量主要体现在下地壳，剖面北段下地壳厚度约为30 km，剖面南段下地壳厚度仅为15 km左右；上地幔顶部局部位置P波速度值偏低，一般为76～78 km/s，反映出云南地区是典型的构造活动区的特点.剖面沿线地壳内地震反射发育，其中莫霍强反射出现在景云桥下方；在景云桥弧形断裂带8～10 km深处出现宽约50 km的强反射带.     

CGP叠加柱面波偏移成像方法

针对松辽盆地薄砂层油藏的地震勘探问题,提出了一种共检波器接收点(CGP)叠加柱面波偏移成像方法。该方法对小炮点距、小检波器点距、中间放炮观测系统采集地震资料,经CGP道集叠加组合成柱面波剖面;采用下行波射线法向下延拓和上行波波动方程向下延拓的方法,使柱面波剖面偏移成像。通过模型分析和对松辽盆地TK8157测线资料进行处理证明该方法的地震分辨率和保真度较高,在发现小砂体、小断层、地层尖灭等方面有较好的效果。     

Fine upper crustal structure of Jiashi strong earthquake swarm region in Xinjiang inferred from high resolution seismic refraction profile data

Introduction Jiashi-Artux area in southwest Xinjiang is one of the most active earthquake provinces at pre-sent in Chinese mainland. In the last century, about 3/4 strong earthquakes in Chinese mainland hit this area, and especially from January 21 to April 16 in 1997, 7 earthquakes with the magnituderanging from 6.0 to 6.9 occurred in a very small area of 9 km×18 km near Jiashi (ZHU et al, 1998). It has never taken place before in Chinese mainland that a series of strong earthquakes shoo…     

三维CT成像的数学模型

三维CT成像广泛应用于放疗模拟定位等临床实践。当扫描运动物体时三维图像存在的位移和形变,与扫描参数设置和被扫描物体的运动状态等关系密切。本文通过理论分析CT扫描过程,建立三维成像的数学模型,计算三维图像的时间分辨率、位移和形变等指标,并分析其变化规律,为将来进一步的实验研究奠定基础。