色散磁导率对异向介质中的调制不稳定性的影响

基于Drude模型研究了异向介质的色散磁导率对调制不稳定性的影响. 结果表明，在反常色散情形，赝五阶非线性在异向介质的负折射区中增大了调制频谱的范围及增益值，这与常规正折射介质中出现的现象正好相反；自陡峭效应在异向介质中有可能为负值，但无论正负，也无论在正折射区还是负折射区，它都抑制调制不稳定性的产生；二阶非线性色散效应在正、负折射区中分别促进和抑制调制不稳定性的产生. 在正常色散情形，由于二阶非线性色散效应的作用，使本来在常规正折射介质中不可能出现的调制不稳定性现象也能出现，这一特性为在正常色散区形成孤     

基于高阶统计量的系统的盲辨识

通过对二阶统计量和高阶统计量的系统辨识方法的比较,重点介绍基于高阶统计量的系统盲辨识,分FIR和IIR两种情况简要描述了在这两种结构中实现系统盲辨识的方法,同时作为盲辨识的一个重要方面,也对系统的时延估计进行了讨论。随着通信和现代信号处理技术的发展,将高阶统计量的观点应用于MIMO系统的辨识已成为一个研究热点。     

Second-order subgradients of convex integral functionals

The purpose of this work is twofold: on the one hand, we study the second-order behaviour of a nonsmooth convex function defined over a reflexive Banach space . We establish several equivalent characterizations of the set , known as the second-order subdifferential of at relative to . On the other hand, we examine the case in which is the functional integral associated to a normal convex integrand . We extend a result of Chi Ngoc Do from the space to a possible nonreflexive Banach space . We also establish a formula for computing the second-order subdifferential .

     

Mechanism Study for Thermal/Electric Field Poling of Fused Silica

On the basis of the experimental reports, the mechanism of the second-order susceptibility ⁽²⁾ for the thermal/electric field poling of fused silica is analyzed, and expressions for ⁽²⁾ are detailedly derived and numerically calculated for the first time. By comparison the theoretical value of ⁽²⁾ with the experiment results, we propose that the effective ⁽²⁾ is created via both the interaction of the intense electric field with the third-order susceptibility ⁽³⁾ and the dipole orientation. The theoretical results show that, in the differently applied voltage, the dipole orientation and ⁽³⁾ play different role in the formation of ⁽²⁾. This theory successfully explains some experiment results.     

激子自旋弛豫对简并量子点发射光子对纠缠度的影响

利用粒子数运动方程和量子回归理论，计算了单个半导体量子点双激子体系脉冲激发下粒子在各能级间辐射跃迁的二阶交叉相关函数以及系统发射光子对的偏振密度矩阵.分析了激子态能级简并量子点体系发射光子对偏振纠缠特性，讨论了纠缠度随激子态间自旋弛豫的变化关系.研究表明，激子自旋弛豫会破坏该系统发射光子对的纠缠度. 关键词： 纠缠光子对 半导体量子点 二阶相关函数     

Semi-infinite programming,duality, discretization and optimality conditions†

The aim of this article is to give a survey of some basic theory of semi-infinite programming. In particular, we discuss various approaches to derivations of duality, discretization, and first- and second-order optimality conditions. Some of the surveyed results are well known while others seem to be less noticed in that area of research.     

Femtosecond second-order solitons in optical fiber transmission

A propagation of the femtosecond second-order solitons in an optical fiber is studied. We show that a generalized nonlinear Schrödinger equation well describes the propagation of the second-order soliton even containing only a few optical cycles. The propagations of a 50 fs and a 10 fs second-order soliton in an optical fiber are numerically simulated. It is found that, for the case of 10 fs second-order soliton, the soliton decay is dominated by the third-order dispersion, in contrast to the case of 50 fs second-order solitons, where the soliton decay is dominated by the delayed Raman response. It is also found that the exact delayed Raman response form must be used for the propagation of the 50 fs or less than 50 fs second-order soliton.     

Wide-band amplitude control of the second-order oscillator circuit

In this paper, a new analysis technique of an ordinary second-order oscillator which is based on multi-time concept is proposed. This mathematical analysis results in a new closed-form solution of a system complete response. It is found that amplitude of the natural response is not constant but varied with the forced response of the system. For a constant forcing function proposed, the new analysis is identical to the conventional analysis. In the case of time-varying forcing function, however, it is different from the conventional approach. Based on such analysis, it implies that the amplitude of a second-order oscillator can easily be controlled by forced response of the system. Hence, the obtained result based on the proposed analysis technique provides a proper mathematical solution for the system, especially in a time-varying forcing function. Moreover, the mathematical analysis for the wide-band characteristic of a second-order oscillator is also described. The experimental results demonstrate the responses of the oscillator which agree well between the theoretical and simulation results.     

Sharp Estimates of Bounded Solutions to Some Second-order Forced Dissipative Equations

Résumé A l’aide d’inégalités différentielles, on établit une estimation proche de l’optimalité pour la norme dans de l’unique solution bornée de u′′ + cu′ + Au = f(t) lorsque A = A ^* ≥ λ I est un opérateur borné ou non sur un espace de Hilbert réel H, V = D(A ^1/2) et λ, c sont des constantes positives, tandis que . By using differential inequalities, a close-to-optimal bound of the unique bounded solution of u′′ + cu′ + Au = f(t) is obtained whenever A = A ^* ≥ λ I is a bounded or unbounded linear operator on a real Hilbert space H, V = D(A ^1/2) and λ, c are positive constants, while .

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