光纤中高阶项对光孤子传输的影响

本文从修正的高阶非线性薛定谔方程出发,分别讨论了光纤中高阶项,诸如线性高阶色散效应、非线性高阶色散效应和自感应喇曼效应对光孤子传输的影响,并介绍了这些高阶项对光纤孤子传输综合影响的结果和光纤孤子通信的应用前景。     

光子晶体光纤超连续谱高阶孤子分裂的数值模拟

基于高阶非线性薛定谔方程,利用分布傅里叶方法（SSFM）数值模拟了高阶孤子在光子晶体光纤反常色散区中的传输。从脉冲形状和频谱两个方面分析讨论了三阶色散、自陡峭效应和脉冲内拉曼散射对高阶孤子传输的影响。计算结果表明：高阶效应使高阶孤子的演化不再具有周期性特性。其中,对高阶孤子分裂起主导作用的是三阶色散和孤子内拉曼散射。高阶效应均使最终频谱得到了不同程度的展宽。     

光孤子传输的能量、动量特性研究

求解了含高阶效应的孤波方程,由此孤子解得到光孤子的能量、动量表达式,并讨论了高阶效应对孤子通信的综合影响。     

高阶飞秒孤子演化特性的数值研究

本文以高阶非线性薛定谔方程为数学模型,数值研究了高阶色散和高阶非线性效应影响下高阶飞秒孤子的演化特性,并与高阶皮秒孤子的演化特性进行了比较.结果发现二阶飞秒孤子的演化特性与二阶皮秒孤子的演化特性非常相似,都具有很好的周期性;而三阶和四阶飞秒孤子的演化特性与相应的皮秒孤子的演化特性有很大不同,高阶效应的存在不同程度上破坏了三阶和四阶孤子演化的周期性.     

光纤放大器中的孤子传输特性

本文求解了含高阶色散和双光子吸收效应的ＮＬＳ方程，由此孤子解讨论了高阶色散和双光子吸收效应对光纤放大器孤子传输的影响。     

高阶效应和光孤子能量,动量

本文根据用普通数学方法求得含高阶效应的ＮＬＳ方程的孤子解计算了光孤子能量，动量后，得到它们与高阶效应的关系式。     

高阶色散对光孤子及孤子对传输的影响分析

为了研究高阶色散对光孤子及孤子对传输的影响,采用分步傅里叶变换方法,对含高阶色散效应与不考虑高阶色散情况下的光孤子非线性薛定谔方程进行了数值求解,得到了孤子脉冲形状与色散阶数有着相关性这一结果.结果表明,奇数阶色散效应会使孤子及孤子对脉冲发生单边振荡,产生能量损耗,并在振荡侧产生次脉冲,而偶数阶色散效应会使孤子及孤子对脉冲发生明显的脉宽展宽,高阶色散效应对孤子脉冲的影响随阶数的增加而减弱.     

高阶效应下矢量暗孤子传输特性研究

本文研究高阶效应下矢量暗孤子的传输特性,导出了矢量暗孤子在三阶色散和五阶非线性效应下的参数演化方程组和孤子两分量间的有效相互作用能的表达式,讨论了高阶效应对孤子传输特性和孤子两分量间相互作用的影响.     

高阶效应对ED—NALM中超短光孤子放大的影响

文中就掺铒光纤放大环镜（ED—NALM）中高阶效应对飞秒级超短光孤子放大的影响进行了详细的数值计算。数值计算表明采用掺铒光纤环镜能有效消除高阶非线性效应对光孤子的不利影响;同时发现通过提高光纤环镜增益值,可以有效抑制高阶效应对掺铒光纤环镜的影响。     

一类迭加态光场的高阶压缩

本文研究了我们前文中提出的光场迭加态的高阶压缩与振幅平方压缩,其结果表明,这两类高阶压缩都可在没有二阶压缩和反聚束效应时出现,从而由这一个侧面反映出了二阶压缩、高阶压缩、振幅平方压缩与反聚束效应等相互之间的独立性。     

High-order ar estimation method of ARMA power spectrum

In this paper, the high-order AR estimation method of ARMA power spectrum and the whitened-noise decision order criterion of AR order are presented. It is indicated that the quality of high-order AR estimation is related to the ill-condition problem and the algorithmic stability of numerical calculation in the paper. The latter can be solved well by using the recurrence algorithm of Householder transform in the solution of high-order AR parameter estimation.     

光纤放大器中孤子的量子效应

利用含时Hartree近似法得到光孤子在含光纤损耗、双光子吸收、三阶色散效应的光纤放大器中传输时的量子非线性薛定谔方程,在一定条件下,有量子态的孤子解,并由此方程讨论了经典和量子效应对孤子在光纤放大器中传输时的影响,由此进一步发现,光场算符的量子力学平均值是一系列修正的经典孤子的叠加。     

Efficient low-frequency inversion of 3-D buried objects with large contrasts

An efficient inversion method is proposed using Cui et al.'s high-order extended Born approximations to reconstruct the conductivity object function of three-dimensional dielectric objects buried in a lossy Earth. High-order solutions of the object function are obtained, which have closed-form relations to the linear inverse-scattering solution. Because such relations can be evaluated quickly using the fast Fourier transform, the high-order solutions have similar simplicity as the linear inversion. When the contrasts of buried objects are large, the high-order solutions are much more accurate due to the approximate consideration of multiple-scattering effects within the objects. Hence, good-resolution images can be obtained for large-contrast objects using the new method by only solving a linear inverse problem. Numerical experiments have shown the validity and efficiency of the proposed method.     

Noise reduction in recursive digital filters using high-order errorfeedback

The problem of solving the optimal (minimum-noise) error feedback coefficients for recursive digital filters is addressed in the general high-order case. It is shown that when minimum noise variance at the filter output is required, the optimization problem leads to set of familiar Wiener-Hopf or Yule-Walker equations, demonstrating that the optimal error feedback can be interpreted as a special case of Wiener filtering. As an alternative to the optimal solution, the formulas for suboptimal error feedback with symmetric or antisymmetric coefficients are derived. In addition, the design of error feedback using power-of-two coefficients is discussed. The efficiency of high order error feedback is examined by test implementations of the set of standard filters. It is concluded that error feedback is a very powerful and versatile method for cutting down the quantization noise in any classical infinite impulse response (IIR) filter implemented as a cascade of second-order direct form sections. The high-order schemes are attractive for use with high-order direct form sections     

高斯粗糙表面低掠入射散射特性研究

该文针对传统解析法不能有效求解低掠入射下粗糙表面散射特性的问题,提出了一种高阶解析法,该算法基于表面散射场的高阶分量和表面轮廓函数的高阶Taylor级数展开。利用该算法,定量比较了同极化的高、低阶散射系数,讨论了低掠入射下不同粗糙度的散射特性,分析了低掠入射下高阶微扰法和高阶基尔霍夫法求解高斯粗糙面的修正效应,得出了高阶解析法可以很好求解低掠入射问题的结论。最后,还研究了同极化散射指数与掠入射角幂函数的拟合问题,修正了极化散射指数的经典表达式。     

高阶非线性微结构固体中的扭结与反扭结孤立波及其存在条件

基于一维微结构固体的高阶非线性波模型,用动力系统的定性分析方法,分析了微结构固体中可能存在的扭结与反扭结孤立波以及它们的存在条件。分析结果表明,在适当条件下高阶非线性和反常频散的微结构固体中可以存在扭结和反扭结孤立波。文中明确给出了这些孤立波的存在条件。用数值方法分析了微结构固体的高阶微尺度非线性效应对扭结与反扭结孤立波的影响。结果表明,随着高阶微尺度非线性效应的负增强（或正增强）,扭结与反扭结孤立波变得越来越陡峭（或平缓）,但它们的幅度保持不变。     

高阶旋转波近似方法及其对任意强度耦合的多光子J－C模型的应用

本文通过分析量子绝热近似与旋转波近似的相似性，提出了计算非旋转波效应的高级旋转波近似方法。应用这个方法，我们研究了任意强度耦合的多光子Ｊ－Ｃ模型的演化，给出了此模型的一阶近似解和任意高阶方程解的递推公式．应用零级解，我们给出了有限温度条件下原子平均能量的演化公式。     

The computational performance of a high-order coupled FEM/BEMprocedure in electropotential problems

This paper presents a thorough analysis of the computational performance of a coupled cubic Hermite boundary element/finite element procedure. This C1 (i.e., value and derivative continous) method has been developed specifically for electropotential problems, and has been previously applied to torso and skull problems. Here, the behavior of this new procedure is quantified by solving a number of dipole in spheres problems. A detailed set of results generated with a wide range of the various input parameters (such as dipole orientation, location, conductivity, and solution method used in each spherical shell [either finite element or boundary elements]) is presented. The new cubic Hermite boundary element procedure shows significantly better accuracy and convergence properties and a significant reduction in CPU time than a traditional boundary element procedure which uses linear or constant elements. Results using the high-order method are also compared with other computational methods which have had quantitative results published for electropotential problems. In all cases, the high-order method offered a significant improvement in computational efficiency by increasing the solution accuracy for the same, or fewer, solution degrees of freedom.     

高阶色散和高阶非线性效应对准光孤子传输的影响

为了研究高阶色散和高阶非线性效应对其在普通光纤上传输的影响,用数值模拟的方法研究了三阶色散、自陡效应和脉冲内拉曼散射效应对准光孤子传输的影响.结果表明准光孤子在实际的普通光纤中传输时,三阶色散、自陡效应和脉冲内拉曼散射效应中,冲内拉曼效应对其传输产生的影响比较大,致使准光孤子在普通光纤上传输时脉冲不断展宽,脉冲峰值功率降低,不能长距离保持脉冲形状不变.