Diffusion and coupled fluxes in concentrated alloys under irradiation: a self-consistent mean-field approach

When an alloy is irradiated, atomic transport can occur through the two types of defects which are created: vacancies and interstitials. Recent developments of the self-consistent mean field (SCMF) kinetic theory could treat within the same formalism diffusion due to vacancies and interstitials in a multi-component alloy. It starts from a microscopic model of the atomic transport via vacancies and interstitials and yields the fluxes with a complete Onsager matrix of the phenomenological coefficients. The jump frequencies depend on the local environment through a ‘broken bond model’ such that the large range of frequencies involved in concentrated alloys is produced by a small number of thermodynamic and kinetic parameters. Kinetic correlations are accounted for through a set of time-dependent effective interactions within a non-equilibrium distribution function of the system. The different approximations of the SCMF theory recover most of the previous diffusion models. Recent improvements of the theory were to extend the multi-frequency approach usually restricted to dilute alloys to diffusion in concentrated alloys with jump frequencies depending on local concentrations and to generalize the formalism first developed for the vacancy diffusion mechanism to the more complex diffusion mechanism of the interstitial in the dumbbell configuration. To cite this article: M. Nastar, C. R. Physique 9 (2008).     

New approach to solution of photorefractive transport equations

In our work we propose a novel method of analysis of photorefractive transport equations. The method based on a perturbative approach can be used in the case of two wave mixing and four wave mixing geometry, i.e. for the samples illuminated by interference patterns. Presented approach can be employed for a broad range of material and experimental parameters, particularly for arbitrary depth of light modulation pattern. The approximate analytical solution is compared with results of numerical calculations and a good agreement practically in every case was found. Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Šwinoujście, Poland     

从古代东西方两种数学思想体系看当代软件开发方法中的两派之争

本文叙述了古代东西方两种数学思想体系的异同,特别分析了东方数学思想体系的直观性和实用性等特点,并指出了这两种数学思想体系与当代软件开发方法中的形式化方法和非形式化方法的两派之争之间的密切联系。     

广东石灰岩植物区系一新种及一新记录种

报导广东省石灰岩植物区系的一个新种，封开钟萼草（玄参科）及一个新记录种，济新乌桕（大戟科）．     

粒径对气固流化床操作特性的影响

分析比较了常温和高温条件下颗粒粒径对气回流化床中最大稳定气泡尺寸的影响规律，从而得到不同温度水平下一定颗粒粒径的流化床可能出现腾涌现象的床层高径比范围，为流化床反应器选择合理的颗粒粒径提供了一定的理论依据．     

多级安全RDBMS的安全策略

讨论了计算机系统的安全策略和多级安全的概念．提出了多级安全ＲＤＢＭＳ的一种安全策略，对策略中的自主安全、多级安全和最小特权原则进行了详细的叙述．     

连杆机构准动力学分析的统一建模方法

探讨了基于构件真实质量分布的连杆机构准动力学（动态静力学）分析的统一建模方法，它适用于各种平面、空间连杆机构．采用达朗伯原理和矩阵方法，推导了机构支反力及驱动力求解的统一公式．开发了相应的准动力学通用分析系统，该系统已有效地应用于工程实际之中．     

均布载荷下固支加筋板结构的大变形

对计及膜力影响、受均布载荷的四周固支矩形加筋板组合结构进行了刚塑性大变形分析．首先对变形模态建立了判别条件；进而根据变形模态和塑性铰线的内能耗散获得了残余变形的估算公式．经实例计算，并与ＡＤＩＮＡ程序计算结果作了比较，获得了变形模态和最大残余变形值均相当一致的好结果．     

解约束优化问题的一类广义共轭方向法：一种几何处理

运行微分几何方法将无约束最优化中的共轭方向法推广到约束最优化问题上。在约束子流形上诱导了一类新的仿射联络使原来的约束最优化问题转化为约束流形上的无约束的局部二次规划问题。从而形成了具有广义共轭方向的一种曲搜索算法。     

随机变幅加载下疲劳强度可靠性分析

目前的疲劳强度及其概率分布是根据等幅Ｐ－Ｓ－Ｎ曲线族求得的，只能用于等幅加载，不能用于变幅及随机加载，而等效应力法又是根据常规ＭＩＮＥＲ准则进行转换的，无法用于可靠性分析，本文首次明确提出等幅疲劳强度，变幅疲劳强度及随机加载疲劳强度的概念，并且运用二维概率ＭＩＮＥＲ法则，通过建立变幅及随机加载的Ｐ－Ｓａ－Ｓｍ－Ｎｖ曲面族方程，提出了变幅及随机加载下疲劳强度可靠性分析的一套系统方法，具有重要的工程尖