预处理JFNK方法求解非平衡辐射扩散方程组

分别采用四种半隐式离散方法构造预处理.针对一维辐射扩散方程组,采用预处理的Jacobian-free Newton-Krylov(PJFNK)求解.数值结果表明预处理方法能够很好地改进JFNK方法的收敛行为.     

CHARACTERIZATION OF POLYCRYSTALLINE GRADIENT THIN FILM BY X-RAY DIFFRACTION METHOD

A direct method is proposed to quantitatively characterize the structural depth profiles emerged in the polycrystalline thin films based on the information obtained by X-ray diffraction (XRD) with various incident angles and treated by a numerical procedure known as the constrained linear inversion. It should be noted that the proposed method was neither sensitive to the random noise appearing in experiment nor to the error originated from the measured thickness of the specimen. To testify the validity of the method, XRD measurements were carried out on a specially designed Pd/Ag bilayer sample, which was annealed at 490℃ for 20 min, and the depth profiles were accordingly calculated through resolving the obtained XRD patterns. The elemental concentration depth profile of the Pd/Ag bilayer sample was in turn calculated from the resolved patterns, which was in good agreement with those obtained by Auger electron analysis on the annealed sample.     

Effects of Localized Interface Phonons on Heat Conductivity in Ingredient Heterogeneous Solids

Phonons are the primary heat carriers in non-metallic solids. In compositionally heterogeneous materials, the thermal properties are believed to be mainly governed by the disrupted phonon transport due to mass disorder and strain fluctuations, while the effects of compositional fluctuation induced local phonon states are usually ignored.Here, by scanning transmission electron microscopy electron energy loss spectroscopy and sophisticated calculations, we identify the vibrational properties of in...