Impact of the self-steepening effect on soliton spectral tunneling in PCF with three zero dispersion wavelengths

This work presents a numerical investigation of the self-steepening(SS) effect on the soliton spectral tunneling(SST) effect in a photonic crystal fiber(PCF) with three zero dispersion wavelengths. Interestingly, the spectral range and flatness can be flexibly tuned by adjusting the SS value. When the SS coefficient increases, the energy between solitons and dispersion waves is redistributed, and the red-shifted soliton forms earlier in the region of long wavelength anomalous dispersion. As a consequence, the SST becomes more obvious. The findings of this work provide interesting insights in regard to the impact of the SST effect on tailored supercontinuum generation.     

广义严格对角占优矩阵的判定条件

给出了广义严格对角占优矩阵的等价表征和判定条件，推广和改进了文献[1-3]的相应结果。     

对冲火焰流场的二维分布对层流火焰传播速度测量的影响

在φ=0.6～0.75的条件下,利用PⅣ测得对冲火焰的二维速度场,分析使用偏移中心线一定距离提取的轴线速度分布曲线所得到的层流火焰传播速度SOL与沿中心线提取的速度分布曲线得到的SOL之间的误差大小.实验结果表明,在弱火焰时对冲火焰速度场具有明显的二维效应.φ=0.6,偏离中心轴线5 mm时,相对误差达到33%;而φ=...     

WLAN一体化安全简析

对WLAN系统的安全系统进行简析,参考802.11系列规范,分析中国推出的WAPI安全标准进行分析。研究WLAN安全系统的发展方向。     

中学生英语写作修辞模式探析

目前,中国学生的英语写作修辞模式呈现出似中非中、似英非英的状态,这一现象的表现形式是多样的,产生原因也是复杂的。本文通过分析中学生英语作文,从主题阐述和论证方式两方面,例举英语学习者写作中存在的修辞模式问题,并分析问题产生的原因。     

时间尺度上Herglotz变分原理及其Noether定理

Herglotz变分原理的作用量是由微分方程定义的,不仅可以描述所有经典变分原理能够描述的动力学过程,还可以对经典变分原理不能适用的非保守系统或耗散系统进行变分描述．时间尺度上微积分理论提供了一种可同时研究离散系统和连续系统的有效方法．本文结合Herglotz变分原理和时间尺度微积分理论来研究时间尺度上的Herglotz变分原理及其Noether定理．首先,给出时间尺度上Lagrange系统的Herglotz变分原理．其次,根据Herglotz变分原理和Dubois-Reymond引理,推导出时间尺度上Lagrange系统的Herglotz变分问题的运动微分方程．再次,基于时间尺度上Hamilton-Herglotz作用量在群的无限小变换下的不变性,给出Noether对称性的定义并导出其Noether等式．最后,建立了时间尺度上Lagrange系统的Herglotz变分问题的Noether定理,给出了连续和离散两种情况下基于Herglotz变分问题的Noether守恒量．文末举例说明结果的应用．     

Noether Symmetry and Conserved Quantities of Fractional Birkhoffian System in Terms of Herglotz Variational Problem

The aim of this paper is to study the Herglotz variational principle of the fractional Birkhoffian system and its Noether symmetry and conserved quantities. First, the fractional Pfaff-Herglotz action and the fractional PfaffHerglotz principle are presented. Second, based on different definitions of fractional derivatives, four kinds of fractional Birkhoff’s equations in terms of the Herglotz variational principle are established. Further, the definition and criterion of Noether symmetry of the fractional Birkhoffian system in terms of the Herglotz variational problem are given. According to the relationship between the symmetry and the conserved quantities, the Noether’s theorems within four different fractional derivatives are derived, which can reduce to the Noether’s theorem of the Birkhoffian system in terms of the Herglotz variational principle under the classical conditions. As applications of the Noether’s t heorems of the fractional Birkhoffian system in terms of the Herglotz variational principle, an example is given at the end of this paper.     

基于遗传算法的G蛋白偶联受体(GPCR)家族的分类预测研究

G蛋白偶联受体广泛参与各类生理活动的调控,目前市场上1/2的小分子药物均是以GPCR为药物靶标。由于G蛋白偶联受体晶体结构缺乏,采用理论方法对G蛋白受体耦合特异性进行分类预测在药物研发领域有着重要的学术和应用价值。因此,本文采用模式识别方法,基于GPCR序列,以伪氨基酸算法以及遗传算法为基础,用支持向量机方法建立了G蛋白偶联受体耦合特异性的预测模型,取得了可达82.5%的较高的预测准确度。