共查询到20条相似文献，搜索用时 15 毫秒
1.
Kenneth F. Kramer 《Physics and Chemistry of Minerals》1983,9(2):49-56
The equations relating element distribution and pH are derived for systems containing an ideal solid solution in equilibrium with an ideal aqueous solution, assuming no polymeric complexes form in the aqueous solution and the solid solution does not contain molecular units with multiple atoms of the substituting elements. These expressions demonstrate that the ratio of the partition coefficients describing element distribution for a system containing a multi-component solid solution is inversely proportional to the solubilities of the end member components at any given pH raised to the power equal to the ratio of the sum of the stoichiometric coefficients of the end-member salt to the stoichiometric coefficient of the substituting radical. The coefficient describing distribution between the aqueous phase and a two-component solid solution is equal to the inverse of the ratio of the end member solubilities raised to the above power. Element distribution between the two phases will be homogenous at any pH resulting in identical solubilities for the two end-member components, and a reversal in relative solubilities will result in a corresponding reversal in the element preferentially incorporated into the solid solution. Because of the dependence of element distribution on pH, a crystal could develop both zoning and reverse zoning as a result of changes in pH. The distribution coefficient could provide information regarding the pH of the aqueous solution at the time of mineral formation if independent evidence establishes the ratio of end-member components in the aqueous phase. The equations describing element distribution may be expressed in terms of the solubility products of the end-member components and the ionization constants of the substituting radicals. Based on the relative values of the ionization constants, pH intervals can be established in which only the concentration of a single complex for each substituting radical need be considered. Within such an interval, the curve of the log of the distribution coefficient vs. pH is linear with a slope equal to the difference in the charges of the two complexes. This approach to the examination of element distribution is developed in some detail for the geologically important case of a two component solid solution having composition (A2+, B2+) X2?. 相似文献
2.
随机介质热弹性力学模型球坐标问题的解析解 总被引：2，自引：0，他引：2
针对随机介质热弹性力学模型,在随机韦泊分布和指数分布下,提出了一种解决随机概率分布用连续函数表示的方法,并推导出该模型球坐标问题的解析解。通过算例,对随机模型与均质模型热应力的区别做了详细研究,结果表明随机概率分布参数m对随机模型的热应力有重要影响。 相似文献
3.
红黏土是一种富含胶结作用物质的塑性黏土,与普通黏性土相比,红黏土的强度特性更为复杂。通过直剪仪对不同含水率和不同含丙三醇溶液的重塑红黏土进行了抗剪强度试验,发现红黏土的强度、黏聚力随着溶液含量的增加出现了“双峰”值现象,且内摩擦角基本保持不变,用丙三醇溶液替代水溶液配制的土样其强度有了明显的降低。结合核磁共振仪对红黏土试样的孔径分布研究情况,基于Bishop提出非饱和土的有效应力原理,探讨了非饱和红黏土的强度随含水率变化出现“双峰”现象的影响机制,认为红黏土本身孔径大小分布特征起了非常重要的作用。 相似文献
4.
S. D. Priest 《Rock Mechanics and Rock Engineering》2004,37(5):347-368
Summary The paper outlines a new method for estimating the distribution form, and mean size, of discontinuities from scanline data. By assuming that the discontinuities are circular discs it has been possible to apply existing solutions for the distributions of censored semi-trace lengths sampled by a scanline at an exposed rock face. These solutions have been implemented by numerical quadrature in a standard Excel spreadsheet, with solution optimisation achieved with Solver. Problems caused by a singularity in the integration were overcome by applying an integration offset parameter. A trigonometrical substitution for removing this singularity is also outlined. The numerical quadrature strategy was validated by comparison with the analytical solution for the uniform distribution, and by comparison with the results of an extensive geometrical simulation of the stereological process. A new distribution, here named the Wicksell distribution, has been identified. This distribution is characterised by the fact that the distribution of disc diameters and the distribution of complete traces on a cutting plane are identical. Two examples, based on real scanline data, are presented to illustrate the practical application of the new methods. 相似文献
5.
鄂尔多斯盆地中南部三叠系延长组8油层组成岩作用及其对储层物性的控制 总被引：1，自引：0，他引：1
鄂尔多斯盆地中南部延长组8油层组主要成岩作用包括压实作用、石英次生加大、自生绿泥石膜生长、次生高岭石化、连晶方解石交代、长石溶蚀。根据铸体薄片,碳氧同位素分析,确定了各种主要成岩产物的空间分布和成因,分析了成岩产物分布与现今总面孔率的关系,从而确定8油层组的物性主要受石英次生加大、连晶方解石、长石溶孔、剩余原生孔隙分布的控制。石英次生加大和连晶方解石发育的地方,储层物性差;具自生绿泥石膜的剩余原生孔隙和长石溶孔发育的地方,储层物性好。 相似文献
6.
7.
8.
本文评述了条形均布荷载下横观各向同性弹性地基中附加应力的诸户［２］解析解和近似解，并提出了笔者的近似简化公式，该公式简明地显示出附加应力在分布规律上与各向同性地基之异同点，可供工程界方便地加以利用。 相似文献
9.
10.
An oblique factor analysis solution for the analysis of mixtures 总被引：2，自引：0，他引：2
Thomas L. Clarke 《Mathematical Geology》1978,10(2):225-241
The problems involved in the factor analysis of data consisting of measurements of material quantity or proportion are discussed, and the inability of existing factor analysis solutions to properly model such data is pointed out. A new factor analysis solution using the linear programming technique is presented which properly analyzes mixture data. A numerical example is presented in which a body of suspended sediment grain-size distribution data is analyzed using the new factor analysis solution. FORTRAN-IV subroutines for computing this solution are included in an Appendix. 相似文献
11.
The evolution of a system of electrons with a given initial distribution in an external magnetic field is considered. An equation describing the evolution of the electron distribution function in a uniform magnetic field is derived for the case of arbitrarily relativistic electrons, and an exact solution to this equation is found. Asymptotics of this solution corresponding to the cases of synchrotron radiation and relativistic dipole radiation are calculated, and the evolution of the radiation spectra for these limiting cases is analyzed. The curvature of the magnetic field lines is taken into account phenomenologically, which demonstrates the presence of an exponential dependence in the case of synchrotron radiation. 相似文献
12.
组构选择性孔隙是塔中地区良里塔格组台地边缘相油气储集层的重要孔隙类型,目前该类型的孔隙在层序地层格架内的分布特征仍不清晰。作者在前人建立的层序地层格架的基础上,通过大量的岩心、薄片、测井及地震资料的分析,在塔中地区良里塔格组台地边缘相识别出7类主要组构选择性孔隙: 粒内溶孔、粒间溶孔、铸模孔、粒间孔、窗格孔、生物体腔孔及格架孔。高频层序中,组构选择性孔隙在90%的礁(丘)滩复合体中上部的大气淡水渗流带—潜流带中成层集中发育,厚度10~40 m,且各类型孔隙纵向上分布特征不同。受研究区湿润的古气候、相对海平面的频繁波动、台地边缘礁滩相较大的沉积速率及较好的初始渗透性等因素控制,组构选择性孔隙的发育具有层位性、旋回性及区块差异性等分布规律。即组构选择性孔隙层主要发育在高位体系域内沉积的良三段—良一段中;纵向上发育5期,主要分布在进积型准层序组6、8及9中,其次是加积型准层序组5、7、10;自东向西,各井区孔隙层数量、厚度及物性均逐步降低,主要孔隙类型由粒内溶孔、铸模孔、粒间溶孔及体腔孔逐渐变为以窗格孔、粒内溶孔及粒间溶孔。 相似文献
13.
14.
《International Geology Review》2012,54(8):1209-1217
Velocities distribution in the overburden and coordinates of the reflecting plane are shown to be simultaneously obtainable in principle, even if the propagation velocities of elastic waves are not known. Travel-time curves for two different points of the excitation, both of which represent the same part of the reflecting plane, are sufficient for a definite solution of this problem. Its exact solution is possible, in case the propagation velocity in the overburden is constant, under certain conditions. -- V.P. Sokoloff. 相似文献
15.
传统土拱效应理论是基于松动区内土体应力均匀分布这一基本假定建立的,然而由于松动区内部主应力轴偏转的影响,实际情况下松动区内部的土体应力分布往往是非均匀的。针对这一情况,在太沙基松动土压力分析模型的基础上,通过假定3种不同形状的大主应力轨迹线,考虑了松动区内应力分布形式对松动土压力的影响,对传统太沙基松动土压力公式进行了修正,并与离散元数值模拟结果进行了对比验证。研究结果表明：当土体达到极限平衡状态时,松动区内部竖向应力与水平向应力分别呈上凹式分布和上凸式分布,松动区中轴线上侧向土压力系数等于被动土压力系数;采用不同形状的大主应力轨迹线进行计算所得应力分布之间的差异在10%以内,且均与离散元数值模拟结果吻合良好,从而验证了修正解的有效性。为计算方便起见,推荐相关工程中采用圆弧形大主应力轨迹线假定进行计算。 相似文献
16.
Molecular simulation of the magnetite-water interface 总被引：1，自引：0，他引：1
This paper reports molecular dynamics simulations of the magnetite (001)-water interface, both in pure water and in the presence of a 2.3 molal solution of NaClO4. The simulations are carried out using a potential model designed to allow the protonation states of the surface functional groups to evolve dynamically through the molecular dynamics trajectory. The primary structural quantities investigated are the populations of the surface functional groups, the distribution of electrolyte in the solution, and the surface hydrogen bonding relationships. The surface protonation states are dominated by extensive hydrolysis of interfacial water molecules, giving rise to a dipolar surface dominated by FeOH2+-OH2-OH− arrangements. Triply coordinated, more deeply buried, surface sites are inert, probably due to the relative lack of solvent in their vicinity. The electrolyte distribution is oscillatory, arranging preferentially in layers defined by the solvating water molecules. The presence of electrolyte has a negligible effect on the protonation states of the surface functional groups. Steady-state behavior is obtained for the protonation states of the surface functional groups and hydrogen-bonding network. Although the overall structure of the electrolyte distribution is fairly well established, the electrolyte distribution has not fully equilibrated, as evidenced by the asymmetry in the distribution from the top to the bottom of the slab. 相似文献
17.
18.
19.
通过分析单桩成桩后桩周土体固结的边界条件和初始条件,建立了饱和黏土中单桩桩周横观各向同性土体的空间轴对称固结问题的定解条件,应用数学物理方法求得该问题的级数解答。通过土体固结与桩承载力的时效性之间的关系,利用承载力的实测资料换算得到的等效固结度,验证了解答的合理性和适用性。同样,应用级数解答求得的桩周土体的固结度可用于桩的承载力的时效分析。 相似文献
20.
太行山北段多金属矿床有3个金属元素富集带:1.中心(铜)钼矿带,形成斑岩型矿床;2.过渡带铁-铜、银-铜、铁和锌成矿带,形成矽卡岩型矿床;3.外带铅-锌-银带,形成脉状矿床.这种分带出现于多个矿区,但不同矿区显示出独特变化.一般以其中一个矿带最发育,其它两矿带次之,但有时也有两矿带相对发育.围绕花岗岩的金属元素区域分布,流体包裹体温度测定及H、O和S同位素分析结果,表明岩浆热液与冷的大气降水(含少量源于围岩的CO2和H2S)之间的混合作用可以解释金属元素沉淀及时空分带的形成. 相似文献