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51.
52.
作为机载SAR极化合成孔径雷达数据应用必不可少的步骤,SAR辐射定标将图像像素值转化为地物的后向散射系数。利用点目标进行辐射定标的方法具有简单、易于操作的特点且具有一定精度,被人们广泛应用于实际的生产中。三面角反射器稳定性较好且易于操作,并拥有较大的散射截面积,在较宽的角度变化范围内其在雷达系统中的散射截面积变化较小,所以被当成最常用的点目标定标器。本文在阐述点目标辐射定标的基础上,以四川省丹棱县为实验区域,进行基于点目标的辐射定标外定标,得出了该方法具有一定精度且简单实用的特性。 相似文献
53.
地震地层解释系统开发研究 总被引:7,自引:3,他引:4
颜琰 《物探化探计算技术》2000,22(1):40-47
机会的出现,往往并没有立刻被注意到,特别是在不熟悉的地区进行新的勘探。如何抓住机会,迅速有效地工作并尽可能多的利用相关信息迅速得出结论,这里所介绍的地震地层解释技术(Stratimagic)为我们提供了快速有效的工作方法和手段。 相似文献
54.
L. Zühlsdorff V. Spieß C. Hübscher H. Villinger A. Rosenberger 《International Journal of Earth Sciences》2000,88(4):655-667
A high-resolution seismic survey was carried out at the accretionary prism on the continental slope off Vancouver Island,
Canada. Two GI-Gun data sets with different source frequency ranges of 50–150 and 100–500 Hz were combined with 4 kHz narrow-beam
echosounding data (Parasound). The data allow spatial correlation between a gas hydrate bottom simulating reflector (BSR)
and distinct areas of high near-sea-floor reflectivity. An integrated interpretation of the multi-frequency data set provides
insight into the regional distribution of tectonically induced fluid migration and gas hydrate formation in the vicinity of
ODP Leg 146 Sites 889 and 890. The BSR at the base of the gas hydrate stability field is observed within accreted and deformed
sediments, but appears to be absent within bedded slope basin deposits. It is suggested that these basin deposits inhibit
vertical fluid flow and prevent the formation of a BSR, whereas the hydraulic conductivity of the accreted sediments is sufficiently
high to allow for pervasive gas migration. An elevation of the BSR beneath the flanks of a topographic high is interpreted
as an indicator for local upflow of warm fluids along permeable pathways within outcropping accreted sediments. Parasound
data reveal discontinuous zones of high reflectivity at or directly beneath the sea floor, which may indicate local cementation
of surface sediments. In combination with GI-Gun data, the occurrence of these reflective areas can be related to the location
of slope sedimentary basins acting as hydraulic seals. It is proposed that the seals sometimes fail along faults extending
beneath the BSR, leading to focused upflow of methane-bearing fluid and the formation of carbonate pavements at the sea floor.
Received: 9 November 1998 / Accepted: 6 April 1999 相似文献
55.
基于连续小波变换的天然气水合物层地震数据多尺度分析——布莱克海台USGS95-1测线应用实例 总被引:2,自引:1,他引:1
似海底反射(BSR)是目前天然气水合物层识别的主要依据,但是当BSR不明显或者缺失的时候怎样识别水合物层,以及水合物层顶面和下伏游离气层底面如何确定,仍然是水合物识别中难以圆满解决的两大难题。以布莱克海台USGS95-1测线地震数据为例利用小波变换进行多尺度研究发现水合物层和游离气层表现出不同的尺度特征:水合物层表现出大尺度特征,而游离气层具有小尺度特征;在最佳尺度剖面上,水合物层表现为低尺度背景中的近似平行于海底的高尺度带。利用水合物层和游离气层的这种尺度差异不但可以识别水合物层,而且还可以推断水合物层的顶面和游离气层的底面。 相似文献
56.
3-D multi-parameter type traveltime tomography in a spherical coordinate frame: comparison of double and triple class simultaneous inversions 下载免费PDF全文
It is now common practice to perform simultaneous traveltime inversion for the velocity field and the reflector geometry in reflection/refraction tomography, or the velocity field and the hypocenter locations in regional earthquake tomography, but seldom are all three classes of model parameters updated simultaneously. This is mainly due to the trade-off between the different types of model parameters and the lack of different seismic phases to constrain the model parameters. Using a spherical-coordinate ray tracing algorithm for first and later(primary reflected) arrival tracing algorithm in combination with a popular linearized inversion solver, it is possible to simultaneously recover the three classes of model parameters in regional or global tomographic studies. In this paper we incorporate the multistage irregular shortest-path ray tracing algorithm(in a spherical coordinate system) with a subspace inversion solver to formulate a simultaneous inversion algorithm for triple model parameters updating using direct and later arrival time information.Comparison tests for two sets of data(noise free and added noise) indicate that the new triple-class parameter inversion algorithm is capable of obtaining nearly the same results as the double-class parameter inversion scheme. Furthermore,the proposed multi-parameter type inversion method is not sensitive to a modest level of picking error in the traveltime data, and also performs well with a relatively large uncertainty in earthquake hypocentral locations. This shows it to be a feasible and promising approach in regional or global tomographic applications. 相似文献
57.
射电天线指向精度通常要求小于主波束宽度的1/10, 对于短厘米波段或毫米波段的大口径反射面天线, 指向精度要求高达几个角秒, 对于天线性能目标的实现是个巨大的挑战, 因此对于大口径高频段的反射面天线来说指向问题成为天线性能实现的重要关注焦点. 在众多影响天线指向精度的结构子系统因素中, 对主反射面变形因素的研究很少. 文章结合天线的结构特点建立了反射面空间坐标系统, 并基于变形后主面点的空间坐标值, 提出了3自由度下的非线性最小二乘吻合的方法去精准预测天线指向. 最后利用空间几何关系严格推导出了服务于天线指向误差修正的俯仰和方位的精确调整量, 从而构建了主面变形同指向误差之间的间接关系, 这对大型射电天线指向精度的提升具有一定的指导意义. 相似文献
58.
根据L/C双频共面SAR能够获取同一海域双波段电磁波后向散射系数,得到更多海洋目标特征信息的电磁散射特点,结合地球物理模型函数研究了一种新的SAR海面风场反演方法。利用L/C双频共面SAR的L和C两个波段的地球物理模型函数和后向散射系数等信息,通过地球物理模型函数联立以及构建和求解最小代价函数,直接从SAR数据本身获取海面风场信息,并借助辅助数据去除了风向的180°模糊,从而实现海面风场反演。仿真分析和海上机载同步飞行试验的研究结果表明,该方法可直接利用SAR数据本身获取精度较高的海面风速、风向;绝对辐射定标精度是决定海面风场反演精度的关键因素,海面风场反演误差随定标精度提高而减小;随着海面风速的增大,风速反演误差逐渐增大。论文提出的双频共面SAR海面风场反演方法解决了传统单波段单极化SAR海面风场反演存在的固有问题,机载同步飞行试验的海面风速和风向反演结果与调查船观测值的均方根误差分别为0.93 m/s和19.39°,可为星载SAR海面风场反演业务化和载荷研制提供支持。 相似文献
59.
Gautam Dadhich Shweta Sharma Mihir Rambhia Aloke K. Mathur P. R. Patel Alpana Shukla 《国际地球制图》2019,34(6):586-596
This study presents the results obtained from image quality assessment of Radar Imaging SATellite (RISAT-1). Image quality parameters such as spatial resolution, peak to sidelobe ratio (PSLR) and integrated sidelobe ratio (ISLR) are calculated by the analysis of impulse response function (IRF) of the point target. The study is carried out to assess temporal stability and consistency of image quality parameters obtained from analysis of IRF of 44 point targets. The results obtained from this study show that the mean values of the range and azimuth resolution are 2.048 ± 0.081 m and 3.383 ± 0.097 m for RH and 1.981 ± 0.081 m and 3.348 ± 0.076 m for RV, respectively. PSLR/ISLR values for RH channel are obtained as ?26.492 dB/?26.823 dB for azimuth and ?19.209 dB/?19.921 dB for the range. For RV channel, PSLR/ISLR values are ?26.300 dB/?27.572 dB for azimuth and ?19.146 dB/?19.827 dB for range. 相似文献
60.
A comprehensive study of the data profiles, including the 2D seismic data, single channel seismic data, shallow sections,
etc., reveals that gas hydrates occur in the East China Sea. A series of special techniques are used in the processing of seismic
data, which include enhancing the accuracy of velocity analysis and resolution, estimating the wavelet, suppressing the multiple,
preserving the relative amplitude, using the DMO and AVO techniques and some special techniques in dealing with the wave impedance.
The existence of gas hydrates is reflected in the subbottom profiles in the appearance of BSRs, amplitude anomalies, velocity
anomalies and AVO anomalies, etc. Hence the gas hydrates can be identified and predicted. It is pointed out that the East China Sea is a favorable area of
the gas hydrates resource, and the Okinawa Trough is a target area of gas hydrates reservoir. 相似文献