变系数非线性Schr(o)dinger方程的孤子解及其相互作用

在光孤子通信和Bose-Einstein凝聚体动力学研究中,求解广义非线性Schr(o)dinger方程是一个重要的研究方向.稳定的孤子模式具有潜在的应用,可为实验技术的实现提供依据.本文引进一种相似变换,将变系数非线性Schr(o)dinger方程转化成非线性Schr(o)dinger方程,并利用已知解深入研究变系数非线性Schr(o)dinger方程解的单孤子解、两孤子解和连续波背景下的孤子解.同时通过选择不同的具体参数,给出它们的图像分析和相应的讨论.     

变系数非线性Schrdinger方程的孤子解及其相互作用

在光孤子通信和Bose-Einstein凝聚体动力学研究中,求解广义非线性Schrdinger方程是一个重要的研究方向.稳定的孤子模式具有潜在的应用,可为实验技术的实现提供依据.本文引进一种相似变换,将变系数非线性Schrdinger方程转化成非线性Schrdinger方程,并利用已知解深入研究变系数非线性Schrdinger方程解的单孤子解、两孤子解和连续波背景下的孤子解.同时通过选择不同的具体参数,给出它们的图像分析和相应的讨论.     

光纤中变系数非线性Schrdinger方程的孤子解及其应用

基于推广的立方非线性Klein_Gordon方程对一般形式的变系数非线性Schrdinger方程进行研究,讨论了无啁啾情形的孤子解,发现了包括亮、暗孤子解和类孤子解在内的一些新的精确解.同时对基本孤子的色散控制方法进行了简单讨论.作为特例,常系数非线性Schrdinger方程和两类特殊的变系数非线性Schrdinger方程的结果和已知的形式一致.此外,还研究了一个周期增益或损耗的光纤系统,得到了有意义的结果.     

光纤中变系数非线性Schr(o)dinger方程的孤子解及其应用

基于推广的立方非线性Klein—Gordon方程对一般形式的变系数非线性Schrodinger方程进行研究，讨论了无啁啾情形的孤子解，发现了包括亮、暗孤子解和类孤子解在内的一些新的精确解．同时对基本孤子的色散控制方法进行了简单讨论．作为特例，常系数非线性Schrodinger方程和两类特殊的变系数非线性Schrodinger方程的结果和已知的形式一致．此外，还研究了一个周期增益或损耗的光纤系统，得到了有意义的结果．     

变系数非线性Schrödinger方程的孤子解及其相互作用

在光孤子通信和Bose-Einstein凝聚体动力学研究中,求解广义非线性Schrödinger方程是一个重要的研究方向.稳定的孤子模式具有潜在的应用,可为实验技术的实现提供依据.本文引进一种相似变换,将变系数非线性Schrödinger方程转化成非线性Schrödinger方程,并利用已知解深入研究变系数非线性Schrödinger方程解的单孤子解、两孤子解和连续波背景下的孤子解.同时通过选择不同的具体参数,给出它们的图像分析和相应的讨论. 关键词： 非线性Schrö dinger方程 相似变换 变系数 孤子解     

耦合Schr(o)dinger系统的周期振荡折叠孤子

引入对称延拓和非线性变换,将(G′/G)展开法扩展到研究(1+1)维非线性耦合Schr(o)dinger系统,构造出该系统的一些分离变量形式的精确解.通过对解中的任意函数进行适当的设置,获得了两类周期振荡折叠孤子.     

具有色散系数的(2+1)维非线性Schrdinger方程的有理解和空间孤子

非线性Schrdinger方程是物理学中具有广泛应用的非线性模型之一.本文采用相似变换,将具有色散系数的(2+1)维非线性Schrdinger方程简化成熟知的Schrdinger方程,进而得到原方程的有理解和一些空间孤子.     

非均匀交换各向异性铁磁介质的非线性表面自旋波

利用Landau-Lifshitz 方程，研究了具有非均匀交换各向异性的半无限大铁磁体的非线性表 面自旋波理论。导出了部分钉扎纯交换铁磁介质的磁化强度所满足的边界条件和非线性表面 自旋波的色散关系，并获得了自旋波振幅沿z方向驻波的一维非线性Schrdinger方程和包 络振幅沿平面传播的二维非线性Schrdinger方程，结果表明铁磁体磁化强度的包络振幅随时空变化的性质是由二维非线性Schrdinger方程决定的。因此预言铁磁介质的表面非线性激发应是二维孤波的形式。对于弱非线性表面自旋波，对非线性Schrdinger方程存在孤子形式解的可能性作了讨论. 关键词： 表面自旋波 Landau-Lifshitz方程 非线性Schrdinger方程 孤子     

蛋白质分子链的非线性激发的孤子模型的一个改进解

通过仔细考察蛋白质分子链中体系运动方程的非线性项,得到了一个与通常非线性Schrdinger方程不同的修正的非线性Schrdinger方程,并求得了一个改进孤子解.     

改进的tanh函数方法与广义变系数KdV和MKdV方程新的精确解

利用改进的tanh函数方法将广义变系数KdV方程和MKdV方程化为一阶变系数非线性常微分方 程组-通过求解这个变系数非线性常微分方程组，获得了广义变系数KdV方程和MKdV方程新的 精确类孤子解、有理形式函数解和三角函数解- 关键词： 改进的tanh函数方法 类孤子解 有理形式函数解 三角函数解     

溶剂化的热力学集团展开理论

把二元溶液的过剩内能（ｅｘｃｅｓｓ ｅｎｅｒｇｙ）分成溶剂－溶剂、溶剂－溶质及溶质－溶质相互作用部分。利用集团展开方法给出了二元溶液在正则系综的配分函数的表达式,利用该表达式得到了溶质的偏摩尔内能（ｐａｒｔｉａｌ ｍｏｌａｒ ｅｎｅｒｇｙ）和偏摩尔熵（ｐａｒｔｉａｌ ｍｏｌａｒ ｅｎｔｒｏｐｙ）的表达式。在无限稀溶液情形,过剩偏摩尔内能的溶剂－溶剂部分又称重组织内能（ｒｅｏｒｇａｎｉｚａｔｉｏｎ ｅｎｅｒｇｙ）,它反映了溶质存在时对其周围溶剂分子之间的相互作用能的影响。研究表明,在溶质的粒子数密度相对较大时,溶质分子之间的相互作用将影响过过剩偏摩尔内能的溶剂－溶剂部分,对于稀溶液,过氧偏摩尔内能的溶剂－溶剂部分与溶质的摩尔分数成线性关系。对低蜜度二元溶液,溶质的过剩偏摩尔内能和过剩偏摩尔熵也与溶质的摩尔分数成线     

内窥镜校正中棋盘格标志点自动提取方法

为了解决具有大畸变内窥镜标定的标志点提取困难和人工参与较多等问题,提出了一种简单快速准确的棋盘格标志点提取方法。该方法是采用粗提取和优化来完成棋盘格标志点的提取的:首先利用高斯滤波去除图像噪声,并计算两次图像的梯度特征,利用梯度极值约束得到粗提取的角点;然后利用棋盘格标志点的对称特点消除噪声点的影响,并得到优化的角点位置。实验结果表明,该方法简单易行,计算量小,不需要人工干预即可获得全部标志点,反投影误差小于0.2pixel。     

Figure of merit for spectrometers for EDXRF

How should one select the best detector for a particular measurement in energy dispersive X‐ray fluorescence (EDXRF)? How should one select the optimum system configuration, i.e. the best shaping time and beam current? Manufacturers provide a variety of specifications, such as energy resolution and maximum count rate, but these are indirectly related to the end use of an EDXRF instrument, the measurement and detection limit of the measured elemental concentrations. We suggest in this paper using the time required to achieve a given statistical uncertainty as a figure of merit. We derive scaling rules for this figure of merit based on conventional specifications, including energy resolution, peaking time, maximum count rate, detector area, and intrinsic efficiency. These scaling rules also include the peak to background ratio of a photopeak and the number of overlapping peaks. We then show how this figure of merit can be used to select the optimum detector and spectrometer configuration for specific applications and compare the results to data obtained with typical systems. Copyright © 2012 John Wiley & Sons, Ltd.     

Memory for pitch versus memory for loudness

The decays of pitch traces and loudness traces in short-term auditory memory were compared in forced-choice discrimination experiments. The two stimuli presented on each trial were separated by a variable delay (D); they consisted of pure tones, series of resolved harmonics, or series of unresolved harmonics mixed with lowpass noise. A roving procedure was employed in order to minimize the influence of context coding. During an initial phase of each experiment, frequency and intensity discrimination thresholds [P(C) = 0.80] were measured with an adaptive staircase method while D was fixed at 0.5 s. The corresponding physical differences (in cents or dB) were then constantly presented at four values of D: 0.5, 2, 5, and 10 s. In the case of intensity discrimination, performance (d') markedly decreased when D increased from 0.5 to 2 s, but was not further reduced when D was longer. In the case of frequency discrimination, the decline of performance as a function of D was significantly less abrupt. This divergence suggests that pitch and loudness are processed in separate modules of auditory memory.     

Requirements for Optical Systems for Virtual Displays

Currently, there are many types of virtual displays and new types arise every year. However, their vast majority appear technically inapplicable because they are inconsistent with a number of key factors related to the eye physiology. In this paper, we present the general requirements for optical systems of virtual displays, taking into account human eye physiology.     

Convolution identities for quasiprobabilities for Bose functions

We present identities relating the equations of motion of various quasiprobabilities for quantum oscillators. These identities turn out useful for checking the consistency of approximations made in constructing the equations of motion with the basic Bose commutator. Moreover, our identities allow to identify the quasiprobability distributions which have the easiest-to-solve equations of motion.     

Microscopic basis for Fick's law for self-diffusion

We investigate self-diffusion in a classical fluid composed of two species which are distinguished through the color of their particles, either black or white, but are identical as regards their mechanical properties. Disregarding color the fluid is in thermal equilibrium. We show that if a single test particle in the one-component fluid moves asymptotically as Brownian motion, then the color density and current in certain classes of nonequilibrium states are related, on the appropriate macroscopic scale, through Fick's law, and the former is governed by the diffusion equation. If in addition several test particles move asymptotically as independent Brownian motions, then the colored fluid is, on a macroscopic scale, in local equilibrium with parameters governed by the solution of the diffusion equation.Part of this work was done while both authors were at IHES, Bures-sur-Yvette, France.Supported in part by NSF Grant No. PHY 78-15920-02.Supported by a Heisenberg fellowship of the Deutsche Forschungsgemeinschaft.     

一种寻找团簇异构体的准动力学方法

建立了一套普遍适用的寻找团簇异构体的准动力学方法，该方法能够迅速给出在一般气相生长条件下形成概率较大的异构体.用该方法得到了C21的异构体谱，并采用分子动力学方法模拟了21个自由的碳原子在氦气氛中形成稳定团簇的过程，表明动力学过程中形成概率较大的异构体都已包含在该方法所得到的异构体谱中.所得到的C21最稳定结构的势能远低于采用遗传算法所得到的结果(Chem. Phys. Lett. 364 213，2002).