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171.
172.
根据水下河床水深点测量采样的既有规则格网法又有三角形法二者优点的四边形法绘制河床等深线图,该法数据结构简单,编程方便,速度快。文 图表对水下对河床水深点的数据数据结构,四边形的构万能主等深线的追踪作了详细的讨论。 相似文献
173.
层序地层研究产生的地层学新观点、新概念和新方法——兼论建立新一代年代地层表 总被引:4,自引:1,他引:3
层序地层学在地层划分、对比、分类和级别体系等地层学根本理论问题上给地层学带来了新认识、新概念和新方法。全球层型剖面和点(GSSP)可建在层序界面的整合部位,从而将传统的自然界线(或不整合面)、层序界面和GSSP三者有机结合起来,使得年代地层界线成为可在野外识别和追索的界线。论证了层序地层是独立存在于岩石地层和年代地层之间的地层类别和包含这三个基本地层类别的新的三重地层分类方案。阐述用层序地层界线优化各类原有年代地层和岩石地层界线的原理和方法,探讨和阐述了新的地层学体系和建立新一代年代地层表的途径和方法。 相似文献
174.
This article describes a method that determines the position of a point relative to a fixed boundary. Its advantage over the other existing algorithms described below is that in most cases it is necessary that only part of the algorithm be executed to determine the position of the point. A possible inconvenience of using this algorithm is that the contour boundary has to be entered as data. For problems where the boundary often changes the algorithm is not suitable in its present form. The applications envisaged here are to cases where the position of a very large number of points have to be determined relative to one fixed polygonal boundary whose shape is known in advance, for example, blanking out of contours in automatic contouring, or selecting drill holes which lie in the particular part of a mineral deposit. 相似文献
175.
WEIWenzhan ZHONGYexun PENGYueying ZHENGHongbo 《地球空间信息科学学报》2003,6(3):62-65
176.
An olivine grain from a peridotite nodule 9206 (Udachnaya kimberlite, Siberia) was investigated by TEM methods including
AEM, HRTEM, SAED and EELS techniques. A previous study of the 9206 olivine sample revealed OH absorption bands in the IR spectrum
and abundant nanometer-sized OH-bearing inclusions, of hexagonal-like or lamellar shape. Inclusions, which are several hundred
nm in size, consist of 10 ? phase, talc and serpentine (chrysotile and lizardite). The lamellar (LI) and hexagon-like small
inclusions of several ten nm in size (SI) are the topic of the present paper. AEM investigations of the inclusions reveal
Mg, Fe and Si as cations only. The Mg/Si and Fe/Si atomic ratios are lower in the inclusions than in the host olivine. The
Si concentration in the olivine host and both lamellar inclusions and small inclusions is the same. A pre-peak at 528eV was
observed in EEL spectra of LI and SI, which is attributed to OH− or Fe3+. From these data it is concluded that there is a OH−- or Fe3+-bearing cation-deficient olivine-like phase present.
HRTEM lattice fringe images of LI and SI exhibit modulated band-like contrasts, which are superimposed onto the olivine lattice.
Diffraction patterns (Fourier-transforms) of the HREM images as well as SAED patterns show that the band-like contrasts in
HRTEM images of the inclusions are caused by periodic modulations of the olivine lattice. Three kinds of superperiodicity
in the olivine structure such as 2a, 3a and 3c, were observed in SAED patterns. The corresponding olivine supercells labelled
here as Hy-2a, Hy-3a and Hy-3c were derived. The M1-vacancies located in the (100) and (001) octahedral layers of the olivine
lattice are suggested to form ordered arrays of planar defects (PD), which cause the band-like contrasts in HRTEM patterns
as well as the superperiodicity in the SAED patterns.
The vacancy concentrations as well as the chemical composition of Hy-2a, Hy-3a and Hy-3c olivine supercells were calculated
using crystal chemical approaches, assuming either {(OH)<
O−V"
Me−(OH)<
O}↔, or {F
e
<
Fe
−H
Me
′}↔ or {2F
e
<
Fe
−V
Me
"}↔ point defect associates. The calculated theoretical compositions Mg1.615Fe+2
0.135v0.25SiO4H0.5 (Hy-2a) and Mg1.54Fe2+
0.12v0.33SiO4H0.66 (Hy-3a and Hy-3c) are in a good agreement with the AEM data on inclusions. Hy-2a, Hy-3a and Hy-3c are considered to be a
hydrous olivine with the extended chemical formula (Mg1-yFe2+
y)2−xvxSiO4H2x. The crystal structure of hydrous olivine is proposed to be a modular olivine structure with Mg-vacant modules. The crystal
chemical formula of hydrous olivines in terms of a modular structure can be written as [MgSiO4H2] · 3[Mg1.82Fe0.18SiO4] for Hy-2a, [MgSiO4H2] · 2[Mg1.82Fe0.18SiO4] for Hy-3a and Hy-3c.
Hydrous olivine is suggested to be exsolved from the olivine 9206, which has been initially saturated by OH-bearing point
defects. The olivine 9206 hydration as well as the following exsolution of hydrous olivine inclusions is suggested to occur
at high pressure-high temperature conditions of the upper mantle.
Received: 15 January 2001 / Accepted: 2 July 2001 相似文献
177.
P. P. Hallan Sanjay Jain K. B. Bhatnagar 《Celestial Mechanics and Dynamical Astronomy》2000,77(3):157-184
The non-linear stability of L
4 in the restricted three-body problem has been studied when the bigger primary is a triaxial rigid body with its equatorial
plane coincident with the plane of motion. It is found that L
4 is stable in the range of linear stability except for three mass ratios:
where A1, A2 depend upon the lengths of the semi axes of the triaxial rigid body.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
178.
179.
一种抗数据压缩的矢量地图数据数字水印算法 总被引:12,自引:4,他引:12
基于矢量地图数据特点,提出了一种抗数据压缩的矢量地图数据数字水印算法,即在嵌入水印信息之前对数据进行道格拉斯-普克法压缩,然后在特征点中嵌入水印信息.实验分析表明,提出的水印算法在抗数据压缩方面具有较好的效果. 相似文献
180.
基于标点随机过程的遥感影像道路提取 总被引:1,自引:1,他引:1
在分析贝叶斯方法用于遥感影像目标提取技术的基础上.基于标点随机过程方法,利用线状地物的整体几何约束和地物之间的空间结构及相关关系对目标构建数学模型.提取线状地物.并以道路网的自动提取为例,详细阐述了此算法。 相似文献