薄板弯曲问题的复合傅里叶级数方法

解析方法与数值方法有效融合是提高计算效能的重要途径．提出薄板弯曲问题的复合傅里叶级数方法．它以解析方法为融合基体,数值方法为融合增强相,是一种新的融合模式．在这种新的融合模式中,傅里叶级数解析解作为变形场的连续表现形式,摆脱了载荷形式和边界条件的强烈依赖性,表现出良好的收敛性态．     

On exchange coupling and bonding in the Gd2@C80 and Gd2@C79N endohedral dimetallo-fullerenes

A series of computational experiments performed with various methods belonging to wave-function and density functional theories approaches the issue of bonding regime and exchange coupling in the title compounds. Gd₂@C₈₀ is computed with a very weak exchange coupling, the sign depending on the method, while Gd₂@C₇₉N has resulted with a strong coupling and ferromagnetic ground state, irrespective of the computational approach. The multi-configuration calculation and broken symmetry estimation are yielding closely coincident coupling constants, of about J ～ 400 cm^?1. No experimental estimation exists, but the ferromagnetic ground state of Gd₂@C₇₉N is confirmed from paramagnetic resonance data. The different behaviour is due to particularities of electron accommodation in the orbital scheme. The exchange effects localised on atom lead to preference for parallel alignment of the electrons placed in the 4f and 5d lanthanide shells, determining also a ferromagnetic inter-centre coupling. The structural insight is completed with a ligand field analysis of the density functional theory results in the context of frozen density embedding. The energy decomposition analysis of bonding effects is also discussed. Finally, with the help of home-made codes (named Xatom+Xsphere), a model for the atom encapsulated in a cage is designed, the exemplified numeric experiments showing relevance for the considered endohedral metallo-fullerene issues.     

一类Euler方程解的渐近行为

给出了一类Ginzburg-Landau型泛函的极小元所满足的Euler方程的解的某些弱收敛性质。     

Spatial Filters on Demand Based on Aperiodic Photonic Crystals

Photonic Crystal spatial filters, apart from stand‐alone spatial filtering function, can also suppress multi‐transverse‐mode operation in laser resonators. Here it is shown that such photonic crystals can be designed by solving the inverse problem: for a given spatial filtering profile. Optimized Photonic Crystal filters were fabricated in photosensitive glass. Experiments have shown that such filters provide a more pronounced filtering effect for total and partial transmissivity conditions.     

对常微分方程初值问题的一种新数值解法的提案

对常微分方程初值问题提出一种新的数值解法,并且研究其误差估计、相容性、稳定性、收敛性,最后进行数值试验.     

基于结构矩阵的DNA序列的相似性模型

通过一维映射把DNA序列转化为时间序列,即把数字1,2,3,4分别分配给组成DNA序列的核苷酸A,T,G,C,用时间序列的结构矩阵来描述DNA序列的结构特征,并根据结构矩阵的一些性质定义了结构矩阵的相似性度量,进而利用结构矩阵之间的相似性度量构建了比较DNA序列的相似性模型,以9个不同物种的β-球蛋白基因的第一个外显子(表1)为例验证了该模型的适用性.并得到了较好得结果.     

Banach空间中不连续非线性Volterra型积分方程的唯一解

本文在一般序Ｂａｎａｃｈ空间中研究了不连续非线性Ｖｏｌｔｅｒｒａ型积分方程的唯一解．在非常弱的条件下证明了非线性Ｖｏｌｔｅｒｒａ型积分方程的唯一解可以由迭代序列的一致极限得到,并给出了逼近解的迭代序列的误差估计式,然后应用到一阶微分方程的初值问题,本质改进并推广了最近的一些结果．     

螺旋折流片强化壳侧传热的四管模型数值模拟

针对螺旋折流片管壳式换热器的正方形布管方式,建立了相间套螺旋折流片的四管数学物理模型,利用FLUENT软件对该模型的流动与传热情况进行了数值模拟;并与光滑通道中及单管螺旋折流片模型的流动和传热结果进行了对比.结果显示旋向相反的相邻螺旋折流片所诱导的两股旋流通过相互作用可提高通道内流体流速,并有效地形成对相邻传热管外的斜向冲刷,这对于减薄边界层,促进近壁流体与主流区流体的动量和质量交换进而强化传热有明显的作用,算例显示其传热系数可比相同尺寸的光管通道中的情形提高约44%～57%.     

approximation for the solutions of stochastic differential equations. iii. jointly weak convergence

We give sufficient conditions for a family Z, e > 0 of continuous finite variation processes to converge weakly to a diffusion process Z. Then we consider the integral equation dXE(t) = (l)(Xe(t))dZE{t) and the stochastic equation dX{i) = (j)(X{t))dZ{t) and denote by X(t,x,w respectively X{t,x,(jo), the solution starting at x. We prove that PoX~l, e>0 converge weakly to Pol     

稳态平板法测导热系数精度的研究

从稳态平板法测导热系数的原理出发,通过对推导过程的近似处理进行有效的修正,得到更为准确的导热系数表达式,并且对数据处理进行了讨论,显示了利用origin软件的数值拟合功能,能够有效的提高散热速率的测量,从而提高了导热系数结果的精度。