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371.
首先介绍了地理信息系统(GIS)网络分析的发展概况;其次在已有GIS最佳遍历分析存在问题的基础上,提出了一种最佳多路遍历分析算法。并在ArcEngine环境下,以某县交通网为例,利用C#.net及ArcEngine二次开发类库实现了其最佳多路灾情巡视路线分析。算法适用范围广,可以推广到很多同类的地理网络问题。 相似文献
372.
373.
依托“西部煤炭资源高精度三维地震勘探技术”工程,对晋城矿区进行了旨在提高小断层,小陷落柱探测能力的高密度三维地震勘探。根据面元选择因素及该区地质任务,采用5m×5m网格进行野外数据采集;考虑炮检距、方位角、覆盖次数、排列片横纵比及煤层埋深(350~500m)等因素,采用中点放炮、60道接收,24次覆盖(横向4次,纵向6次)的8线16炮束状观测系统,基岩中激发。原始资料经同一处理流程后,获得5m×5m×1ms、5m×10m×1ms、10m×10m×1ms及2.5m×2.5m×1ms不同单元的三维数据体多个,通过对比可以发现小断层,小陷落柱在其小面元叠加时间剖面、顺层切片及相干切片都有清晰的反映。实例说明,小面元采集技术可以提高对小构造的纵、横向分辨能力,满足山区对三维地震精确勘探的要求。 相似文献
374.
屯兰矿南五采区地形复杂,最大高差达271m,地表大面积为第四系黄土覆盖,激发困难。为探索研究小面元三维地震勘探技术的应用效果。在常规三维地震勘区域内划出1km^2,采用5m×5m小面元进行采集。在地震数据采集过程中,采取了加大激发井深、提高覆盖次数、减小CMP面元网格和加大接收排列等技术措施,做到“四小三高、二中一深、两个等高面”。通过插值、抽线及扩大面元处理。获得2.5m×2.5m×1ms、5m×5m×1ms、5m×10m×1ms、10m×10m×1ms以及不同叠加次数的三维数据体。资料解释工作主要是在5m×5m×1ms、2.5m×2.5m×1ms两个数据体上进行,解释落差大于或等于5m的断层6条,落差3~5m的断层8条;查明长轴直径20~30m的陷落柱4个。30~100m的陷落柱1个,大于100m的陷落柱3个。与相邻区常规三维地震比较,小面元三维地震勘探有利于对小陷落柱、小断层的控制和解释。 相似文献
375.
R. A. Oktyabrsky A. A. Vrzhosek A. M. Lennikov T. A. Yasnygina S. V. Rasskazov E. Yu. Moskalenko T. A. Velivetskaya 《Russian Journal of Pacific Geology》2008,2(4):325-335
New geochemical data are presented on the magmatic rocks of the Late Jurassic Koksharovka alkaline-ultrabasic massif, which is associated with deposits of vermiculite, apatite, V-bearing titanomagnetite, and placer isoferroplatinum. The REE geochemistry and strontium, oxygen, and carbon isotopic composition of carbonatites and related ijolites and pyroxenites, together with geological observations, point to the magmatic origin of the Koksharovka carbonatites. The origin of associated magmatic rocks is discussed. Trace element modeling of partial melting of mantle sources was conducted to decipher the genesis of the melts of the Koksharovka carbonatites and host titanite-kaersutite pyroxenites. 相似文献
376.
Patterns of crystallographic preferred orientation are referred to as texture. The specific subject of texture analysis is
the experimental determination and interpretation of the statistical distribution of orientations of crystals within a specimen
of polycrystalline material, which could be metals or rocks. The objective is to relate an observed pattern of preferred orientation
to its generating processes and vice versa. In geosciences, texture of minerals in rocks is used to infer constraints on their
tectono-metamorphic history. Since most physical properties of crystals, such as elastic moduli, the coefficients of thermal
expansion, or chemical resistance to etching depends on crystal symmetry and orientation, the presence of texture imparts
directional properties to the polycrystalline material.
A major issue of mathematical texture analysis is the resolution of the inverse problem to determine a reasonable orientation
density function on SO(3) from measured pole intensities on
, which relates to the inverse of the totally geodesic Radon transform. This communication introduces a wavelet approach into
mathematical texture analysis. Wavelets on the two-dimensional sphere
and on the rotational group SO(3) are discussed, and an algorithms for a wavelet decomposition on both domains following the
ideas of Ta-Hsin Li is given. The relationship of these wavelets on both domains with respect to the totally geodesic Radon
transform is investigated. In particular, it is shown that the Radon transform of these wavelets on SO(3) are again wavelets
on
. A novel algorithm for the inversion of experimental pole intensities to an orientation density function based on this relationship
is developed. 相似文献
377.
Rorik A. Peterson 《Mathematical Geosciences》2008,40(3):277-298
Differential frost heave is often implicated in the formation of patterned ground in regions subject to recurrent freezing
and thawing. A linear stability analysis (LSA) indicates that a continuum model of frost heave is linearly unstable under
typical natural freezing conditions of silty-clay soils. A two-dimensional non-linear numerical analysis corroborates the
frozen time LSA results, and also indicates the importance of non-linear and time-dependent terms that ultimately lead to
a preferred mode, which the LSA fails to predict. Instability of the one-dimensional solution occurs at shallow freezing depths
and near-zero surface loads when positive perturbations in the ice content at the freezing front lead to a concomitant increase
in thermomolecular pressure and upward ice velocity. Differential frost heave can then occur because of the increased heat
flux from the perturbed surfaces. A three-dimensional model using random initial surface perturbations indicates that regular
surface patterns will evolve with a length scale in the order of 2–4 meters, which corresponds quite closely with naturally-occurring
non-sorted patterned ground. 相似文献
378.
Inversely-Mapped Analytical Solutions for Flow Patterns around and within Inclined Elliptic Inclusions in Fluid-Saturated Rocks 总被引:1,自引:0,他引:1
Chongbin Zhao Bruce E. Hobbs Alison Ord Shenglin Peng Liangming Liu 《Mathematical Geosciences》2008,40(2):179-197
In this paper, an inverse mapping is used to transform the previously-derived analytical solutions from a local elliptical
coordinate system into a conventional Cartesian coordinate system. This enables a complete set of exact analytical solutions
to be derived rigorously for the pore-fluid velocity, stream function, and excess pore-fluid pressure around and within buried
inclined elliptic inclusions in pore-fluid-saturated porous rocks. To maximize the application range of the derived analytical
solutions, the focal distance of an ellipse is used to represent the size of the ellipse, while the length ratio of the long
axis to the short one is used to represent the geometrical shape of the ellipse. Since the present analytical solutions are
expressed in a conventional Cartesian coordinate system, it is convenient to investigate, both qualitatively and quantitatively,
the distribution patterns of the pore-fluid flow and excess pressure around and within many different families of buried inclined
elliptic inclusions. The major advantage in using the present analytical solution is that they can be conveniently computed
in a global Cartesian coordinate system, which is widely used in many scientific and engineering computations. As an application
example, the present analytical solutions have been used to investigate how the dip angle of an inclined elliptic inclusion
affects the distribution patterns of the pore-fluid flow and excess pore-fluid pressure when the permeability ratio of the
elliptic inclusion is of finite but nonzero values. 相似文献
379.
Changing grading of soil: effect on critical states 总被引:6,自引:3,他引:3
Examples of situations are presented where the grading of a soil changes during its lifetime either by crushing of particles
leading to an increase of fine material or by slow transport of fine particles with seepage leading to a decrease of fine
material. Such grading changes influence the basic constitutive properties of the soil, in particular properties such as critical
states which are dependent on the available range of densities of packing. Discrete element modelling is used to show the
dependence of critical state conditions on grading and the way in which the particle assembly seeks out new critical state
conditions as the grading changes. 相似文献
380.
Characterization of the microseismic activity (M L <2.0) has been performed at Mt. Melbourne since 1990. We recorded a group of low frequency events with common morphological characteristics, i.e., an emerging onset, an unclear second phase and a sharply dropping coda. Spectral analysis of events recorded at more than one station indicates that the seismogram characteristics and spectral content are largely due to source effects. A polarization filter applied to a set of three component data revealed a first phase made up ofP waves followed (after about 0.9–1.4 sec.) by a second phase probably composed ofSH-type waves. Particle motion analysis detected a seismic ray angle direction mainly between N70°E and N110°E and apparent angle of incidence between 35° and 48° for the first phase. The studied seismicity was localized in an area on the eastern slope of Mt. Melbourne Volcano which presents a surface temperature anomaly (Mazzarini andSalvini, 1994). We formulate two hypotheses for the type of earthquakes recorded: 1) long-period events involving active presence of magmatic fluids in the source processes; 2) or the result of fracturing processes (shear?) in a medium characterized by transition between brittle and plastic behaviors. In the latter hypothesis the superficial thermal anomaly may be a symptom of this behavior at depth and is confirmed by the lown values observed for the exponential fit in the codaQ analysis. 相似文献