(2+1)维Nizhnik方程的Jacobi椭圆函数周期解

利用最近提出的F-展开法,导出了(2 1)维Nizhnik方程的由Jacobi椭圆函数表示的周期解,并且在极限情况下,可以推得(2 1)维Nizhnik方程的孤波解以及其他形式解。     

一类变系数偏微分方程的精确解的求法及其计算机机械化实现（英文）

变系数偏微分方程出现在许多物理模型中,在非线性科学领域中有着重要的应用.为了求解某类变系数偏微分方程,本文利用椭圆方程,借助于符号计算软件,构造了辅助椭圆方程方法.新算法的基本思想:只要某个变系数偏微分方程经过合理的变换能变换成椭圆方程的形式,那么该方程的求解问题就会迎刃而解.以变系数Kadomtsev-Petviashvili方程为例,不但说明了该算法的有效性,而且得到了该方程许多新的解,包括暗孤波解、钟形孤波解和雅可比椭圆函数解.这些解可以很好地描述非线性物理现象.     

河床流体模型方程扭状孤波解的渐近稳定性

河床流体模型方程是出现在两相流体动力学中的重要模型,本文研究了该模型单调递减扭状孤波解的渐近稳定性．文中我们首先推导了关于该扭状孤波解的一阶、二阶导数估计,然后再运用恰当的能量估计技巧和Young不等式,克服了该模型复杂耗散项引起的困难,得到了其扭状孤波解关于扰动的一致能量估计,从而证明了该模型单调递减扭状孤波解的渐近稳定性．     

一类非线性(3+1)维波动方程的周期解

通过行波约化一类(3+1)维非线性波动方程和建立与立方非线性Klein-Gordon方程间变换的联系,由此得到其孤立波解和周期解.     

一类非线性(3+1)维波动方程的周期解

通过行波约化一类(3+1)维非线性波动方程和建立与立方非线性Klejn-Gordon方程间变换的联系,由此得到其孤立波解和周期解。     

具任意次非线性项的非线性Klein-Gordon方程孤波解的轨道稳定性

具任意次非线性项的非线性Klein-Gordon方程是一类非常重要的物理模型,它的孤波解的轨道稳定性有着很好的物理意义.本文利用抽象的Grillakis轨道稳定性理论和谱分析,讨论具任意次非线性项的非线性Klein-Gordon方程的孤波解的轨道稳定性.当非线性项的系数以及波速满足一定的条件时,得出了其钟状孤波解总是不...     

Klein-Gordon方程的新行波解

利用一种基于符号计算的代数方法,结合Maple环境中的Epsflon软件包,求解Klein—Gordon方程,获得了若干其它方法不曾给出的形式更为丰富的新的显式行波解,其中包括孤波解、三角函数解、Jacobi椭圆函数周期解和Weierstrass~圆函数周期解．本文用F一展开法求得Klein—Gordon方程的新周期波解和孤波解．     

非线性弦振动的Kdv方程及其速度孤波解

文中用递减微扰法导出了非线性弦振动的 Kdv 方程。文中分析了无色散和无非线性(线性色散)两种特殊情况下的解。然后,详细地讨论了 Kdv 方程的速度孤波解的性态,并指出了非线性弦振动中孤波的主要特征。     

组合KdV-Burgers方程的精确解

用直接方法和假设方法的一种结合得到了组合KdV-Burgers方程的一些显式精确解。包括孤波解、奇异行波解和三角函数状周期波解。这个方程的一些特别重要的情形如组合KdV方程，mKdV-Burgers方程及mKdV方程等也可用此方法精确求解。     

(2+1)维色散长波方程组和组合KdV-Burgers方程的新的精确孤立波解

本文在齐次平衡法、双曲正切函数法和辅助方程法的基础上引入一类新的辅助方程,并借助符号计算系统Mathematica来构造了(2 1)维色散长波方程组和组合KdV-Burgers方程的新的精确孤立波解。这种方法也可用于寻找其它非线性发展方程的新的精确孤立波解。     

收藏基辅（1）

收藏苏联相机,你会明显地感到,199年后,苏联相机的制造地冠名发生了变化。原先,不论是位于莫斯科的克拉斯诺果尔斯克工厂、位于彼得堡的列宁格勒光机工厂、位于哈尔科夫的费特机器制造公司、位于明斯科的白俄罗斯光机工厂、还是位于基辅的阿尔谢纳尔工厂,所有相机无一例外的都用俄文标明苏联制造以及英     

Transmission electron microscope study of the topotactic reaction of (0 0 1), (0 1 1) and (1 1 1) Ag films and Te

The formation, structure and morphology of silver telluride was investigated in the reaction of (0 0 1), (0 1 1) and (1 1 1) single crystalline Ag films with vacuum deposited Te. Silver films 30–40 nm in thickness were deposited by thermal evaporation onto water- and chlorine-treated NaCl. Onto this silver 1–40 nm of tellurium were deposited at 100 and 200 °C. The Ag–Te reaction occurred during Te deposition. Accordingly, formation of the compound phase was investigated from the nucleation stage through complete tellurization on either side of the polymorphic phase transformation temperature (T_c=150 °C). Transmission electron microscope and selected area electron diffraction showed that monoclinic silver telluride (Ag₂Te) of different morphology and texture was always formed. The orientation of silver and monoclinic phase upon differently oriented monocrystalline Ag films and at deposition temperatures around T_c is discussed.     

Molecular dynamics description of silver adatom diffusion on Ag(1 0 0) and Ag(1 1 1) surfaces

The self-diffusion processes of single adatoms on Ag(1 0 0) and Ag(1 1 1) surfaces have been studied using molecular-dynamics simulations and a many-body potential derived in the framework of the second-moment approximation to the tight-binding model. Our results for the (1 0 0) surface indicate that, although the migration energy for hopping is lower than that of the exchange mechanism, the exchange diffusion is higher than hopping diffusion for temperatures above 600 K. The migration energy for the hopping mechanism is in very good agreement with the experiment and the results of ab initio calculations. We also find that for the Ag(1 1 1) face the dominant mechanism is the hopping, which exhibit Arrhenius behaviour with two distinct temperature ranges, corresponding to two different migration energies. The diffusion in the high temperature region is mainly due to correlated jumps requiring an activation energy which is in excellent agreement with the experimental data. In addition the temperature dependence of the mean-square-displacements and the relaxations of both surface atoms and adatoms are presented and compared with previous studies.     

Diffusion of clusters down (1 1 1) aluminum islands

The key factor determining nucleation processes and faceting in homoepitaxial growth as well as texture competition is the mobility of adatoms and small clusters across step edges and facets. Using a combination of molecular dynamics and ab initio calculations, we investigate the mechanisms of small clusters (dimer and trimer) diffusion down the aluminum (1 1 1) surface. In this paper we report results of molecular dynamics studies. Our study shows that the clusters dissociate at the step-edge of compact islands. As a result, the clusters diffuse down the step by an exchange mechanism with a small or medium Schwoebel barrier. The mechanism of this down-diffusion/dissociation is discussed and the corresponding energetics are calculated using the molecular statics method. We find a large anisotropy between the barriers at the two types of 1 1 0 oriented steps.     

SU(1, 1) and SU(2) Squeezing in Trilinear Optical Processes

Abstract

The squeezing properties in terms of SU(1, 1) and SU(2) operators for the case of trilinear processes are studied. The initial state of the system is supposed to be a coherent state in one of the modes and number states in the remaining modes. It is pointed out that in several cases a considerable amount of squeezing can be achieved. Due to the common mathematical structure the case of a two-mode coupler with intensity dependent coupling is also analysed.     

La2/3Sr1/3Mn1-xCuxO3的磁电阻研究

采用溶胶一凝胶(sol-gel)法制备了La2/3 Sr1/3Mn1-x CuxO3(x=0.00、0.05、0.10、0.20)的多晶样品.利用振动样品磁强计测量了样品在室温下的磁性能;利用X射线衍射确定了粉体的组成;利用扫描电子显微镜观察了颗粒的形貌.在1.8T磁场作用下,当x=0时,在370K,样品的磁电阻几乎成...     

The possibility of improving the structural perfection of the new heterojunctions GaAs-(Ge2)1− x (ZnSe)x, Ge-(Ge2)1−x (ZnSe)x, GaP-(Ge2)1−x (ZnSe)x, and Si-(Ge2)1−x (ZnSe)x

Based on morphological investigations, as well as on a study of the scanning patterns and diffraction spectra of the heterostructures GaAs-(Ge₂)_1−x (ZnSe)_x, Ge-(Ge₂)_1−x (ZnSe)_x, GaP-(Ge₂)_1−x (ZnSe)_x, and Si-(Ge₂)_1−x (ZnSe)_x, it is shown that the crystal perfection of these structures depends on the choice of the conditions of liquid-phase epitaxy. It is shown that mirror-smooth epitaxial layers of (Ge ₂)_1−x (ZnSe)_x with the lowest stress levels can be obtained on GaAs (100) and Ge (111) substrates. Pis’ma Zh. Tekh. Fiz. 24, 12–16 (January 26, 1998)     

Optical constants of V(1-x)W(x)O(2) Films

The spectral complex optical constants in the visible and the near-infrared region of VO(2) and V(1-x)W(x)O(2) films deposited on glass substrates were determined from observed reflectance and transmittance spectra for which the least-squares method was used. In the metallic phase, the optical properties were characterized by the Drude model in wavelength regions longer than 750 nm.