Multi-component SC Lax Integrable Hierarchy of Soliton Equations and Its Multi-component Integrable Coupling System with Two Arbitrary Functions

A new simple loop algebra ^-GM is constructed, which is devoted to establishing an isospectral problem.By making use of generalized Tu scheme, the multi-component SC hierarchy is obtained. Furthermore, an expanding loop algebra ^-FM of the loop algebra ^-GM is presented. Based on FM, the multi-component integrable coupling system of the multi-component SC hierarchy of soliton equations is worked out. How to design isospectral problem of mulitcomponent hierarchy of soliton equations is a technique and interesting topic. The method can be applied to other nonlinear evolution equations hierarchy.     

CaCu3Ti4O12 陶瓷介电模量响应特性的研究

由于CaCu₃Ti₄O₁₂巨介电常数陶瓷的低频区直流电导较大, 本文采用模量 M"-f频谱表征与分析了低频和高频的两个松弛极化过程. 研究认为, 这两个特征峰属于晶界区Schottky 势垒耗尽层边缘深陷阱的电子松弛过程, 其中高频松弛峰起源于晶粒本征缺陷的电子松弛过程, 而低频松弛峰则为与氧空位有关的松弛极化过程. 对于CaCu₃Ti₄O₁₂这类低频下具有高直流电导的陶瓷材料, 采用模量频谱能更有效地分析研究其损耗极化机理. 关键词： 3Ti₄O₁₂陶瓷')" href="#">CaCu₃Ti₄O₁₂陶瓷 模量 松弛过程 电导     

Ultrafast Energy Transfer and Enhanced Two-Photon Absorption in a Novel Porphyrin Side-Chain Polymer

Ultrafast relaxation processes and transient two-photon absorption are studied in a novel porphyrin side-chain polymer, 5-hydroxy-10,15,20-triphenyl-porphyrin-poly(glycidyl methacrylate) (HTPP-PGMA), by using picosecond luminescence spectroscopy and femtosecond pump--probe techniques. HTPP-PGMA exhibits the ultrafast initial luminescence decay (～300ps), which is absent in the conventional porphyrin monomer such as TPP. Enhanced two-photon absorption was observed in HTPP-PGMA; the corresponding Im x⁽³⁾ is about 2.8× 10¹¹esu, which is almost one order of magnitude larger than that of the conventional porphyrin monomer (TPP) (～1.3×10¹²esu). The ultrafast energy transfer plays an important role in the excited-state relaxation dynamics observed in HTPP-PGMA. The potential application of HTPP-PGMA in optical switching is discussed.     

一种可压缩流动的高阶加权紧致非线性格式(WCNS)的加速收敛方法

以高超声速粘性绕流的数值模拟为例,研究LU-SGS、高斯-赛德尔点松弛、线松弛以及GMRES等隐式求解方法在空间项采用高阶精度格式WCNS离散时的收敛性,并对GMRES(generalized minimal residual)方法中的子迭代影响作了对比计算.结果表明,采用准确的解析雅克比矩阵的点、线松弛的收敛速度优于LU-SGS,以线松弛为预处理的GMRES算法具有良好的收敛特性.     

High-Frequency Einstein-Podolsky-Rosen Entanglement via Atomic Memory Effects in Four-Wave Mixing

Atomic memory effects occur when the atomic relaxation times are comparable to or much longer than the cavlty relaxation times. We show that by using the memory effects, it is possible to obtain high-frequency Einstein- Podolsky-tlosen entanglement between a pair of Stokes and anti-Stokes fields in a four-wave mixing system. The physical origin is traced to the dynamical Stark splittings of dressed states due to the parametrically amplified fields. This mechanism provides an alternative and efficient way for sideband entanglement.     

双锥/双楔流动中的高温气体效应仿真模拟

在高超声速飞行和再入地球大气过程中, 气体分子的振动、电子态激发, 伴随离解、电离反应, 从而产生高温真实气体效应。不同数值方法对高温真实气体效应的模化会造成气体热物性参数的差异, 从而对流场模拟引入不确定度。以高超声速的双锥/双楔流动为例, 通过计算流体力学方法和直接模拟Monte Carlo (DSMC)方法, 研究高温真实气体模型对复杂干扰流动的预测能力。结果表明, 有别于量热完全气体, 若考虑真实物理过程的热化学非平衡过程带来气体热力学性质、输运特性的变化, 会导致激波角、边界层厚度、分离区尺寸等流动结构的改变。因此, 在研究高超声速模拟中应注意数值模型的正确应用。      

三维曲面腔顶盖驱动流的MRT-LBM研究

采用多松弛时间格子玻尔兹曼方法(MRT-LBM)的D3Q15模型分别对长方体腔、圆柱腔、半圆柱腔、旋转双曲面腔、旋转椭球面腔、半球腔以及两种组合腔体的三维顶盖驱动腔流进行数值模拟, 比较分析各腔体内流线分布、流速等值线分布和涡心的发展, 对于典型腔体模拟不同雷诺数下的流动情况。结果表明: 在同一雷诺数下, 曲面边界不仅能消除从边界产生的次涡, 还会导致腔内主涡的分离, 增大中心纵剖面纵向回流速度; “上长方体+下半圆柱”腔内流函数分布与边界贴合度最高。当雷诺数不断增大时, 半圆柱腔内主涡逐渐分离成两个同向涡, “上圆柱+下半球”腔内始终保持着圆柱腔与半球腔内的基本流动特征; 而长方体腔内主涡涡心保持在同一高度, 次涡逐渐增强, “上长方体+下半圆柱”腔内流动愈加规则, 主涡逐渐下沉, 流速等值线分布逐渐趋于中心小、四周大。     

MOCVD生长的GaN和GaN:Mg薄膜的拉曼散射

通过显微拉曼散射对用金属有机化学气相沉积(MOCVD)法在Al2O3衬底上生长的六方相CaN和掺Mg的P型GaN薄膜进行了研究。在两个样品的拉曼散射谱中同时观察到位于640,660cm^-1附近的两个峰。640cm^-1的峰归因于布里渊区边界(L点)最高声学声子的二倍频,而660cm^-1的峰为布里渊区边界的光学声子支或缺陷诱导的局域振动模。掺Mg的GaN在该处的峰型变宽是Mg诱导的缺陷引起的加宽或Mg的局域模与上述两峰叠加的结果。在掺Mg的样品中还观察到276,376cm^-1几个局域模并给予了解释。同时掺Mg的GaN中出现了应力弛豫的现象,掺Mg引起的失配位错和电子-声子相互作用都有可能对E2模的频率产生影响。     

Observation of β-Relaxation in Sub-Tg Isothermally Annealed Al-Based Metallic Glasses

Al85Ni5 Y8Ca2 and Al88Ni5 Y6Co2Fe2 metallic glasses are fabricated by melt spinning. A kink or a small exothermic peak is observed for both the samples isothermally annealed at sub-glass transition temperatures. Temperature modulated differential scanning calorimetry （TMDSC） data disapprove amorphous phase separation. The activation energies derived from Kissinger plots of the exothermic process on DSC curve around glass transition temperature are consistent with those of β-relaxation of metallic glasses.     

Correlation of Cooperatively Localized Rearrangement on the “Fluidized Domain” of Polymers to Their Nonexponentially Viscoelastic Behaviors at Double Aging Processes (I): A Set of Reduced Universal Equations on the Stress Relaxation Modulus and Creep Comp

基于α-和β-微区、微晶、交联和缠结链组网络结构和非线性粘弹性复相涨落模型,提出了双重(物理和力学)老化下不同尺寸和末端向量高分子链组的流动化微区内关联性局部化重排动力学新理论,它能把初级α-微区的降解作用和次级β-微区的再生效应对剪切速率、尺寸大小和温度依赖性有机结合起来．然后用统计力学和动力学结合法计算了三种不同类型高聚物在等温等压双重老化过程中多元链组的总构象改变自由能,证实了它起源于多元链组的尺寸大小、形状和体积的变化．推导出了它们单向拉伸下的本构方程、应力松弛模量和蠕变柔量表征式以及它们相对应的两组对比态普适方程．结果表明该两组对比态下应力松弛模量和蠕变柔量普适方程均具有同K-W-W伸展指数函数完全一致的形式．最终又建立了该两组对比态普适方程中三个分子参数同老化条件、温度和高聚物起始结构之间的相关性．