光纤弯曲损耗特性的理论与实验研究

为了减小在长距离光纤通信中存在的弯曲损耗和利用光纤激光器中的弯曲损耗获得单模输出，利用速度法解释了光纤弯曲损耗机制，采用Marcuse理论研究了弯曲损耗随弯曲半径、波长和纤芯半径变化的关系。通过计算机仿真和实验得出弯曲损耗随弯曲半径的减小而增大，随波长的增大而增大，随纤芯半径的增大而增大，高阶模式的损耗大于低阶模式。利用这一结论就可以通过控制弯曲半径在临界半径以内来减小通信中的弯曲损耗，通过增大模场半径来实现光纤激光器中的单模输出。     

Kinetic modeling of a high power fast-axial-flow CO2 laser with computational fluid dynamics method

A new computational fluid dynamics (CFD) method for the simulation of fast-axial-flow CO2 laser is developed.The model which is solved by CFD software uses a set of dynamic differential equations to describe the dynamic process in one discharge tube.The velocity,temperature,pressure and turbulence energy distributions in discharge passage are presented.There is a good agreement between the theoretical prediction and the experimental results.This result indicates that the parameters of the laser have significant effect on the flow distribution in the discharge passage.It is helpful to optimize the output of high power CO2 laser by mastering its kinetic characteristics.     

Small compact perturbation of strongly irreducible operators

An operatorT onH is called strongly irreducible ifT is not similar to any reducible operators. In this paper, we shall say yes to answer the following question raised by D. A. Herrero.Given an operatorT with connected spectrum (T) and a positive number , can we find a compact operatorK with K < such thatT+K is strongly irreducible?Supported by National Natural Science Foundation of China(19901011), Mathematical Center of State Education Commission of China and 973 Project of China     

Variational methods for the choreography solution to the three- body problem

In this paper, we give a short proof for the existence of nontrivial choreography solution to the equal-mass three-body problem, which is discovered by Chenciner and Montgomery recently.     

Novel Covalently Linked Self-Assembled Films from a Functional Hyperbranched Conjugated Poly(Phenylene Vinylene)

The hotSPOt in the fields of molecular films focuses on highly ordered, ultrathin filmswith molecularly controllable surface properties. It is attractive tO stUdy supramolecularfunctional POlymeric materials with suitable physical properties and abilities to formorganized superstrUctures at the interfacesl'2'3A. Dendritic macromolecules are a kind ofmaterials which is capable of self-organizing into superstrUctUres'. So a new dendrimerlike POly(Phenylene vinylene)- --hyperbranched conj "…     

A note on holomorphic maps with unipotent Jacobian matrices

We prove that a holomorphic map is invertible if its Jacobian matrix is unipotent.

     

电解沉积的分形维数与ZnSO_4溶液浓度的关系

用电沉积方法得到了不同浓度硫酸锌电解液的分形凝聚图像;进行图像处理,得到了其分形维数与浓度的关系曲线;用粒子扩散限制凝聚模型解释了此关系     

某新型装备维修策略的研究

本文对如何借助于专家的知识、经验,科学、合理地制定某新型武器装备的维修策略进行了研究、探讨,提出了具有军事意义、又具有经济价值的新方法。为该新型装备的贮存、管理提供了决策依据,同时也为其它新型装备维修策略的制定提供了思路。     

综合函数与扩展原理

本文首先对合情扩展映射的公理化条件的完备性与独立性进行讨论,之后给出了扩展原理的一般形式及合情扩展映射的等价定义。最后,利用综合函数,特别是变维综合函数列,给出了扩展原理的一些具体形式     

虚拟仪器技术及乐音的频谱分析

阐述了虚拟仪器技术的概念和特点,精确测量了３ 种乐音信号的波形、频谱和频率