从始态到准稳态过程的数学描述

本文应用数值方法,求解了有限区间非齐次边条件的F-P方程,描述了从始态发展到准稳态的裂变过程.对任何核温度,都能得到稳定的非零裂变速率.     

(Zn、Cd)S:Cu、Br黄色交流电致发光材料的晶体结构和发光特性

本文首次提出一种制备黄色交流粉末电致发光材料的新方法.在以ZnS为基质的绿色材料的基础上,低温扩散CdS,获得系列黄材料.并测量了晶体结构和发光特性.     

钾蒸汽中双光子激发产生2~3∏_g—α~3∑_u~+扩散带受激辐射

本文报道了在K_2-K中通过双光子共振激发原子或双光子激发分子产生2~3∏_(?)—a~3∑_u~+扩散带辐射的实验结果,并对激发机制以及扩散带辐射随激发能量和温度的变化进行了讨论.     

Linearization of Systems of Nonlinear Diffusion Equations

We investigate the linearization of systems of n-component nonlinear diffusion equations; such systems have physical applications in soil science, mathematical biology and invariant curve flows. Equivalence transformations of their auxiliary systems are used to identify the systems that can be linearized. We also provide several examples of systems with two-component equations, and show how to linearize them by nonlocal mappings.     

Group Foliation Method and Functional Separation of Variables to Nonlinear Diffusion Equations

Generalized functional separation of variables to nonlinear diffusion equations is studied in terms of the extended group foliation method. A complete classification for the nonlinear diffusion equation with source term which admits functional separable solutions is presented.     

Thermal Properties of Materials Characterized by Scanning Electron-Acoustic Microscopy

A modified technique of scanning electron-acoustic microscopy is employed to determine thermal diffusivity of materials. Using the dependence of the electron-acoustic signal on modulation frequency of the electron beam, the thermal diffusivity of materials is characterized based on a simplified thermoelastic theory. The thermal diffusivities of several metals characterized by the modified scanning electron-acoustic microscopy are in good agreement with the referential values of the corresponding materials, which proves that the scanning electronacoustic microscopy can be used to characterize the thermal diffusivity of materials effectively. In addition, for micro-inhomogeneous materials, such as biological tissues, the macro-effective （average） thermal diffusivities are characterized by the technique.     

反应扩散系统中波传播的锁频现象

在空间延展系统中,当增强外部光强时,作者观察到波传播的N∶N-1(N≥2)锁频现象.此现象是在光敏BZ反应实验中观察到的.通过构建一个映射函数,发现在波周期和外部光强的关系中存在魔鬼阶梯,并且此阶梯与实验数据相吻合.     

一种可扩展的三维半导体器件并行数值模拟算法

在基于漂移-扩散模型的三维半导体器件数值模拟中,通过有限体积法进行数值离散,采用完全耦合的牛顿迭代求解非线性代数方程组,并使用基于代数多重网格预条件子的GMRES方法求解牛顿迭代中的线性方程组,构造一种稳健且高度可扩展的非结构四面体网格上求解半导体方程的并行算法.基于PHG平台实现该算法的并行计算程序,并对PN结和MOS场效应晶体管等问题进行了最大网格规模达到5亿单元、最大并行规模达到1 024进程的大规模数值模拟实验,结果表明,该算法计算效率高,可扩展性好.     

隐-显积分因子间断Galerkin方法求解二维辐射扩散方程

提出一种求解二维非平衡辐射扩散方程的数值方法.空间离散上采用加权间断Galerkin有限元方法,其中数值流量的构造采用一种新的加权平均;时间离散上采用隐-显积分因子方法,将扩散系数线性化,然后用积分因子方法求解间断Galerkin方法离散后的非线性常微分方程组.数值试验中在非结构网格上求解了多介质的辐射扩散方程.结果表明:对于强非线性和强耦合的非线性扩散方程组,该方法是一种非常有效的数值算法.     

混合工质扩散吸收制冷系统初步实验研究

本文研究了一种混合工质扩散吸收制冷循环,在带溶液泵的循环实验装置上,以R23/R32/R134a为混合制冷剂,He为扩散气体,DMF(二甲基甲酰胺)为吸收剂,进行了实验研究。结果表明,高压侧混合制冷剂在回热器中进一步被低压侧混合制冷剂冷却,使其在更低的温度下液化并与He扩散蒸发,可以实现较低的蒸发温度。中间沸点组分R32可以改善系统的制冷性能,有利于较低蒸发温度的实现。本文提出的水平蛇形套管换热器用作扩散吸收系统回热器是可行的,但还需进一步改进回热器的结构,提高加工工艺和安装精度。