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2.
GPS网络RTK的质量控制 总被引:2,自引:2,他引:0
随着科技的发展与工程应用的深入,传统RTK技术的不足也逐渐体现出来。网络RTK的出现克服了它的局限性。本文简要介绍了网络RTK的概念、工作原理、误差来源与平差、质量控制方法。 相似文献
3.
高空间分辨率遥感影像中地物目标内部光谱信息复杂性的增强,使得传统基于光谱特征值的数据处理方法效果不再显著,影像分割为解决这一问题提供了一种思路,成为当前高空间分辨率遥感影像处理的研究焦点.时刻独立脉冲耦合神经网络具有状态相近、空间相邻神经元相互耦合同步脉冲激发和区域之间神经元脉冲激发时刻独立两大特点,已被应用于非遥感影像分割中,并取得较好效果.本文结合高空间分辨率遥感影像特点,通过对网络参数进行实验和分析,提出一个基于时刻独立脉冲耦合神经网络的高空间分辨率遥感影像分割方法,并利用空间分辨率0.3m的航空影像进行了数据试验,将分割结果进行讨论并与现有时刻独立脉冲耦合神经网络方法和ISODATA方法分割结果进行对比分析.结果表明:时刻独立脉冲耦合神经网络在高空间分辨率遥感影像分割处理中具有很好的应用前景. 相似文献
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Yongshun John Chen 《Pure and Applied Geophysics》1996,146(3-4):621-648
The global mid-ocean ridge system is one of the most active plate boundaries on the earth and understanding the dynamic processes at this plate boundary is one of the most important problems in geodynamics. In this paper I present recent results of several aspects of mid-ocean ridge studies concerning the dynamics of oceanic lithosphere at these diverging plate boundaries. I show that the observed rift valley to no-rift valley transition (globally due to the increase of spreading rate or locally due to the crustal thickness variations and/or thermal anomalies) can be explained by the strong temperature dependence of the power law rheology of the oceanic lithosphere, and most importantly, by the difference in the rheological behavior of the oceanic crust from the underlying mantle. The effect of this weaker lower crust on ridge dynamics is mainly influenced by spreading rate and crustal thickness variations. The accumulated strain pattern from a recently developed lens model, based on recent seismic observations, was proposed as an appealing mechanism for the observed gabbro layering sequence in the Oman Ophiolite. It is now known that the mid-ocean ridges at all spreading rates are offset into individual spreading segments by both transform and nontransform discontinuities. The tectonics of ridge segmentation are also spreading-rate dependent: the slow-spreading Mid-Atlantic Ridge is characterized by distinct bulls-eye shaped gravity lows, suggesting large along-axis variations in melt production and crustal thickness, whereas the fast-spreading East-Pacific Rise is associated with much smaller along-axis variations. These spreading-rate dependent changes have been attributed to a fundamental differences in ridge segmentation mechanisms and mantle upwelling at mid-ocean ridges: the mantle upwelling may be intrinsically plume-like (3-D) beneath a slow-spreading ridge but more sheet-like (2-D) beneath a fast-spreading ridge. 相似文献
6.
Stefan M. Luthi 《Mathematical Geology》1994,26(2):181-196
The texture of digital rock images, as recorded, for instance, with borehole imaging devices, is shown to reflect different bedding types. Textural segmentation of borehole images, therefore, subdivides the recorded sequence into bedding units. We show that a textural segmentation algorithm based on the concept of texture energy achieves good results when compared with synthetic as well as real data in which petroleum geologists have performed zonations on cores. Texture energy involves filtering of the original image with a set of texture sensitive masks. The filtering is done as a finite convolution over the size of the masks. On the resulting images the variance is computed over a relatively large sliding window, which, in its practical implementation, covers the full width of the image. The resulting nine one-dimensional curves are then clustered hierarchically into a user-determined number of image texture or lithological bedding classes. Principal component analysis previous to clustering can be used to reduce redundancy in the data. A recurring and relatively ill-defined problem in this field are macro-textures, i.e., the cyclic interbedding of two or more bedding types. We show that sliding Fourier transforms and variable mask scale can successfully address the zonation of macro-textures. In general, the method gives best results with mask sizes equivalent to 2–4 centimeters, reflecting the length scale at which the investigated geological bedding seems to have its highest variation. 相似文献
7.
F. Bella R. Bella P. F. Biagi M. Caputo G. Della Monica A. Ermini E. Pettinelli V. Sgrigna 《Pure and Applied Geophysics》1993,141(1):125-137
Prototype instrumentation, able to automatically measure groundwater radon content variations, is presented. The equipment is made of stainless steel and has spherical valves with automatic and pneumatic control. The deemanation of the gases from the water is obtained by evacuating a suitable expansion chamber. The instrumentation can make discrete sampling ranging from 1 per hour to 1 per 99 hours. The equipment was tested in the laboratory: the efficiency was measured by means of a266Ra solution. A mean value of (0.65±0.07) count/s/Bq was obtained. A calibration test was carried out by comparing countings from the automatic equipment with those obtained by the standard laboratory cell. Results of an operational check over a period of approximately one year indicate that variations in radon at the calibration site are attributable more to meteorological than to tectonic causes. 相似文献
8.
李刚 《南京气象学院学报》2005,28(2):225-232
几何活动轮廓模型以其计算稳定等优点,被广泛用于图像分割。给出一种基于AOS(additive operator splitting)算法的快速活动轮廓模型,将AOS方法与几何活动轮廓模型相结合构造一种半隐式迭代模型,它对迭代步长没有限制,从而可以选择较大的迭代步长,提高了模型的时间效率,并使用区域信息构造系数矩阵,使模型具有全局性。对MR(magnetic resonance)图像分割的实验表明,该模型可以得到较好的分割结果,同时时间效率也有大幅提高,方便了实时应用。 相似文献
9.
航空影像分割的最小二乘支持向量机方法 总被引:5,自引:0,他引:5
将最小支持向量机LS-SVM用于航空影像的分割,讨论了不同核函数对分割结果的影响和稀疏化处理对决策函数的影响。试验表明了LS-SVM方法用于航空影像分割的可行性。 相似文献
10.
T. J. Reston W. Weinrebe I. Grevemeyer E. R. Flueh N. C. Mitchell L. Kirstein C. Kopp H. Kopp participants of Meteor / 《Earth and Planetary Science Letters》2002,200(3-4):255-269
The structure of the Mid-Atlantic Ridge at 5°S was investigated during a recent cruise with the FS Meteor. A major dextral transform fault (hereafter the 5°S FZ) offsets the ridge left-laterally by 80 km. Just south of the transform and to the west of the median valley, the inside corner (IC – the region bounded by the ridge and the active transform) is marked by a major massif, characterized by a corrugated upper surface. Fossil IC massifs can also be identified further to the west. Unusually, a massif almost as high as the IC massif also characterizes the outside corner (OC) south of the inactive fracture zone and to the east of the median valley. This OC massif has axis-parallel dimensions identical to the IC massif and both are bounded on their sides closest to the spreading axis by abrupt, steep slopes. An axial volcanic ridge is well developed in the median valley both south of the IC/OC massifs and in an abandoned rift valley to the east of the OC massif, but is absent along the new ridge-axis segment between the IC and OC massifs. Wide-angle seismic data show that between the massifs, the crust of the median valley thins markedly towards the FZ. These observations are consistent with the formation of the OC massif by the rifting of an IC core complex and the development of a new spreading centre between the IC and OC massifs. The split IC massif presents an opportunity to study the internal structure of the footwall of a detachment fault, from the corrugated fault surface to deeper beneath the fault, without recourse to drilling. Preliminary dredging recovered gabbros from the scarp slope of the rifted IC massif, and serpentinites and gabbros from the intersection of this scarp with the corrugated surface. This is compatible with a concentration of serpentinites along the detachment surface, even where the massif internally is largely plutonic in nature. 相似文献