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111.
112.
钾含量对白云母X射线衍射特征的影响 总被引:5,自引:1,他引:4
对白云母X射线衍射峰强度的理论计算,发现其衍射峰的强度随钾含量呈规律性变化;对白云母活化释钾后不同钾含量样品进行X射线衍射实验,发现实测的衍射峰强度值与计算值变化趋势一致。计算与实测的白云母特征衍射峰强度比值曲线也有相同的变化趋势。这些结果表明白云母中钾含量是其X射线衍射特征变化的主要原因。 相似文献
113.
The problem of the hydrodynamic interaction with the arc-shaped bottom-mounted breakwaters is investigated theoretically. The breakwater is assumed to be rigid, thin, impermeable and vertically located in a finite water depth. The fluid domain is divided into two sub-regions of inner and outer by an auxiliary circular interface. Linear theory is assumed and the eigenfunction expansion approach is used to determine the wave field. In order to examine the validity of the theoretical model, the analytical solutions are compared to agree well with published results with the same parameters. Numerical results including wave amplitude, surge pressure, and wave force are presented with different model parameters. The major factors including wave parameters, structure configuration, and water depth that affect the surge pressure, wave forces, and wave amplitudes are discussed and illustrated by some graphs and cloud maps. 相似文献
114.
115.
X射线衍射分析法适宜于分析有机显微组分的芳环层的层状结构。有机质的芳环层结构与其类型和演化程度有关。表征有机质芳环层的层状结构的主要参数:高度Lc、宽度La、网面间距dhk1和芳环层层数可作为油气勘探中判断源岩性质、类型、演化程度与生烃潜力的依据。文章还对参数的变化与意义进行了初步讨论。 相似文献
116.
非线性效应对浅水水波变形的影响 总被引:3,自引:0,他引:3
本文采用波数矢量无旋和波能守恒方程建立了一个考虑非线性作用的浅水水波变形数值模型,模型中采用Battjes关系与波数矢量无旋,波能守恒方程一起来求解波浪在浅水中变形的波浪要素,在波能守恒方程中考虑了底摩擦的影响。利用本文提出的数值模型对一个斜坡浅滩水域波浪折射绕射现象进行了验证,验证计算中用一个非线性经验弥散关系近似浅水水波变形的非线性效应并与用线性弥散关系的计算结果进行了比较,结果说明使用非线性 相似文献
117.
Modelling of pile wave barriers by effective trenches and their screening effectiveness 总被引:2,自引:0,他引:2
The three-dimensional problem of isolation of vibration by a row of piles is studied numerically on the basis of a model replacing the row of piles by an effective trench in order to reduce the modelling complexity. The analysis is accomplished with the aid of an advanced frequency domain boundary element method, which is used for both the infilled trench and the soil medium in conjunction with a coupling procedure based on enforcement of equilibrium and compatibility at the trench–soil interface. Linear elastic or viscoelastic material behaviour is assumed for both the piles and the soil. The piles can be tubular or solid and have circular or square cross-section. The vibration source is a vertical force, harmonically varying with time, and the row of piles acts as a passive wave barrier. The effective trench model is constructed by invoking well known homogenization techniques used in the mechanics of fibre-reinforced composite materials, and its accuracy is compared against a rigorous boundary element analysis modelling each pile separately in full contact with the soil medium. On the basis of the effective trench model, the screening effectiveness of a row of piles is studied through parametric studies. 相似文献
118.
黄土/古土壤的物源研究对于揭示第四纪气候变化和青藏高原隆升历史具有重要意义。本研究以位于黄土高原西部1.4 Ma以来的兰州黄土/古土壤沉积序列为研究对象,基于X射线衍射技术分析了黄土/古土壤中的主要矿物组成,侧重于碳酸盐矿物含量,追溯了兰州黄土/古土壤的直接物源。结果显示: (1)1.4 Ma以来兰州地区黄土/古土壤沉积物的主要直接源区为柴达木盆地沙漠区和阿拉善干旱区。(2)基于二元混合模型计算的潜在原始源区对兰州黄土白云石和总碳酸盐矿物的相对贡献率以及长石与石英比值结果一致支持1.4 Ma以来兰州黄土原始物源发生了多次变化。1.4~1.1 Ma和0.9~0.3 Ma青藏高原东北缘造山带(昆仑山、祁连山)和中亚造山带对兰州黄土的贡献相当,而1.1~0.9 Ma和0.3 Ma以来,中亚造山带对兰州黄土的物源贡献增加,这可能分别是对中更新世气候转型和0.3 Ma以来青藏高原及邻近地区干冷气候增强的响应。1.15 Ma和0.8 Ma兰州黄土/古土壤中高的白云石含量、碳酸盐矿物总含量以及0.8 Ma长石与石英比值的快速升高可能是对“昆黄运动”的响应,进而造成了昆仑山、祁连山对黄土高原物源贡献的增加。 相似文献
119.
R. L. Frost J. Kristof G. N. Paroz J. T. Kloprogge 《Physics and Chemistry of Minerals》1999,26(3):257-263
Upon intercalation of both ordered (low defect) and disordered (high defect) kaolinites with acetamide, two types of interaction
are observed. Firstly, hydrogen bonding between the NH2 groups of the acetamide with the siloxane oxygens is formed, as evidenced by the formation of two new bands at 3400 and 3509
cm–1. Secondly, the appearance of additional bands at ∼3600 cm–1 in both the infrared and Raman spectra of the acetamide intercalates is attributed to a second type of hydrogen bonding by
the interaction of the C=O group and the inner surface hydroxyls. Changes in the intensity of the hydroxyl deformation modes
in the 895 to 940 cm–1 region are attributed to the changes in the hydrogen bonding of the kaolinite surfaces. It is proposed that the hydrogen
bonding between the adjacent kaolinite layers is replaced with hydrogen bonding between both kaolinite surfaces and the acetamide
molecule. Changes in the molecular structure of acetamide are observed upon intercalation. The amide 1 band is lost and replaced
with a well-defined NH2 deformation vibration. The loss of the amide 1 band is attributed the hydrogen bond formation between the amide hydrogens
and the siloxane surface. The bands of the C=O group at 1680 and 1740 cm–1 become a single band at 1680 cm–1. The amide 2 band remains unchanged. The lack of intensity of the 1740 cm–1 band is attributed to the formation of hydrogen bonding between the inner surface hydroxyl groups and the carbonyl group.
Received: 4 February 1998/ Revised, accepted: 30 June 1998 相似文献
120.
The crystal structures, lattice dynamics and magnetic properties of synthetic Co-cordierite, Co2Al4Si5O18, and Mn-cordierite, Mn2Al4Si5O18 have been studied by neutron powder diffraction, infrared spectroscopy and magnetisation measurements. Due to different synthesis
conditions, the Co-cordierite used here crystallised in the hexagonal α-cordierite structure with a disordered Si/Al distribution
in the framework, while for the Mn-cordierite the orthorhombic β-structure has been determined. The experimentally determined
paramagnetic moments,
exp
(Mn) = 5.47(6)
B
and
exp
(Co) = 3.88(4)
B
, are in good agreement with theoretical predictions for octahedrally coordinated Mn2+ and Co2+, respectively. In both compounds there is no magnetic long-range order down to at least 1.5 K. However, the onset of an anti-ferromagnetic
short-range correlation of magnetic moments along [001] has been observed for Mn-cordierite by magnetisation and neutron diffraction
measurements. This short-range magnetic correlation becomes evident from diffuse scattering observed at 2 K. The diffuse scattering
has been interpreted in terms of a Blech-Averbach function.
Received: 30 June 1998 / Revised, accepted: 3 March 1999 相似文献