二元系相图中的数学方法

本文介绍绘制二元系各类相图的数学方法。它是把确定相图中分溶曲线的问题,转化为通过确定平面动力系统来确定初值的一条轨线的问题。这样,可以用计算机来绘制二元系的相图。同时也为从相图来研究二端元的活度和活度系数提供了一个新的途径。     

The perturbation method in elastic wave scattering

Methods of theoretical study in seismic wave scattering are reviewed with the emphasis on the perturbation method. Detailed analysis for weak scattering using Born approximation is given. For elastic random media, the mean square amplitudes of scattered waves are derived using a new approach by working directly in the spectrum domain. The conditions for the scalar wave approximation are obtained. The problem of sensitivity of fore- and backscattering to heterogeneities with different scales and properties (velocity or impedance) is discussed.     

Metamorphic evolution of the Bunger Hills, East Antarctica: evidence for substantial post-metamorphic peak compression with minimal cooling in a Proterozoic orogenic event

ABSTRACT The Bunger Hills, East Antarctica, experienced a low-pressure granulite facies orogenic event during the Proterozoic. The stable coexistence of the S1 foliation-parallel M1 assemblages, garnet-cordierite-spinel-ilmenite and garnet-sillimanite-spinel-ilmenite-rutile, in quartz-bearing pelitic gneisses is evidence for metamorphic peak pressures of around 4 kbar during M1, at temperatures of about 800°C. The growth of massive reaction coronas of garnet and cordierite around hercynitic spinel and iron-titanium oxides during M2 is evidence for the destabilization of the M1 assemblages during compression. Thermodynamic calculations on the M2 assemblages indicate formation pressures of 6–7 kbar at temperatures of about 750°C. Thus, the gneisses from the Bunger Hills indicate about 2 kbar or more of compression during minimal cooling. Such a P-T path is different from that of many other Proterozoic terranes which are characterized by isobaric cooling or decompression. A large charnockite body, which is undeformed, was intruded at ～950°C, towards the end of compression. The low pressures during M1 can be best explained by metamorphism at mid-crustal levels in thin continental crust in thin lithosphere above a thermal perturbation in the underlying asthenosphere. We suggest that the compression during cooling was a result of gravitational backflow in which the action of body forces between adjacent normal thickness crust and the thin crust of the Bunger Hills is 'switched on’by the thermal perturbation. Within such a model, the timing of intrusion of the charnockite exposed in the Bunger Hills is consistent with its generation by partial melting during the metamorphic maximum of the lowermost crust.     

测高卫星径向摄动的时域表示

本文首先推导出了量级为ｅ＾｜ｑ｜的Ｇｌｐｑ（ｅ）的显式表达式，给出了Ｇｌｐｏｐ、Ｇｌｐ１和Ｇｌｐ－１和保留至ｅ＾｜ｑ｜＋２项的高阶公式，然后给出了与Ｋａｕｌａ线性解形式相类似的保留至ｅ＾２项的径向摄动公式，最后给出了径向摄动频率与轨道元素摄动频率之间的对应关系。     

天体化学:地球起源与演化的几个关键问题

以近几年天体化学研究取得的一些重要成果，论述了对于认识地球的起源和演化进程的重要意义。地球主要由一套具有独立化学成分组成的硅酸盐质星子群随机碰撞吸积而成。地球的星子堆积形成方式和初始化学成分的不均一性制约着地球后期的非均一、非均变演化过程。以１８００Ｍａ为转折点，地球的演化具明显的两阶段演化特征：早期以初生壳体———星子源地体的形成和发展为特点，后期以岩石圈板块运动为特点。地球演化史中的地外撞击事件，是太阳系形成机制———碰撞吸积作用的继续，是地质历史生物、沉积、岩浆、构造等演化的重要营力之一。     

麻粒岩相条件下蠕状石成因的一种解释

关于蠕状石的成因，施工地质学家提出各种不同的成因假说，多数人认为是交代生成的。根据蠕状石总是产在麻粒岩相变质岩和相应的混合岩中，并常出现于斜长石，正长石和石英的接触部位，含蠕状石的斜长石的折射率低于不含蠕状石的斜工石以及近年来花岗质岩和石熔融实验研究获得的成果，笔者认为，蠕状石是在麻粒岩相变质条件下，由溶熔作用在变质岩中局部产生的花岗质熔浆于冷却结晶过程中最后共结产生的。     

Reflection coefficients for weak anisotropic media

The interaction of plane elastic waves with a plane boundary between two anisotropic elastic half-spaces is investigated. The anisotropy dealt with in this study is of a general type. Explicit expressions for energy-related reflection and transmission coefficients are derived. They represent an approximation which is valid for a small deviation of the elastic parameters from isotropy.
Classical perturbation theory is applied on a 6times6 non-symmetric real eigenvalue problem to calculate first-order corrections for the polarization and stress of the plane waves. The explicit solution of the isotropic problem is used as a reference case. Degenerate perturbation theory is used to consider the splitting of the isotropic S -wave into two anisotropic qS-waves. The boundary conditions for two half-spaces in welded contact lead to a 6times6 system of linear equations. A correction to the isotropic solution is calculated by linearization. The resultant coefficients are functions of horizontal slowness, Lamé parameters and densities of the reference media, and of the perturbation of the elasticity tensors from isotropy.     

正压大气有利发展扰动型与遥相关型的建立

本文讨论了夏季纬向不对称气候平均流下通过正压大气内部动力过程建立遥相关型的问题。首先详细描述和讨论了有利发展扰动型的概念及其计算方法。作为对比，对正规模不稳定进行了分析。结果表明，正规模的不稳定增长率很小，难以用于解释遥相关型的发展。而有利发展扰动型的计算分析表明，最有利发展的那些扰动型的振幅增长率同实际大气遥相关型的增长率相一致，并且这些有利发展扰动型都将演变为同实际大气相一致的遥相关型结构。从而提出了，至少部分实际大气遥相关型可以不依赖于异常外源强迫，而仅依赖于大气内部的正压过程即能量转换过程而建立起来。