A Powerful Simple Shooting Method for Designing Multi-Pumped Fibre Raman Amplifiers

A simple shooting method dedicated to the design of multipump discrete Raman fibre amplifiers (RFAs) ispro posed and discussed in detail. A novel scheme to provide a good initial guess for backward lightwaves is also proposed to improve the efficiency and robustness of the method. Using the proposed method, a discrete RFA with four backward pumps and 93 signal channels is simulated for the maximum number of interaction waves considered simultaneously in the RFA design reported previously; to our best knowledge. The numerical simulation results show that the proposed method is fast and robust. It can be used in the design of RFAs with various configurations including co-, counter- and bi-directJonal-pump schemes to provide an actual modelling.     

Vacuum Fluctuations and Motion of a Charged Test Particle in a Cylindrical Spacetime

The effects of quantum electromagnetic fluctuations upon the motion of a test charged particle are examined in a cylindrical spacetime in which one spatial is compactified. The mean squared fluctuations in the velocity and position of the test particle are calculated. It is found that the random motion of the test particle will be anisotropic. The possible consequences for theories with extra compactified spatial dimensions are discussed.     

Effect of Magnetic Field and Equilibrium Flow on Rayleigh-Taylor Instability

We investigate the effect of a finite equilibrium flow and magnetic field on the Rayleigh-Taylor instability. It is found that the equilibrium flow only makes a frequency shift of perturbation and the growth rate of the Rayleigh-Taylor instability remains unchanged. However, the magnetic field can change the growth rate and, in particular,a very strong magnetic field suppresses the growth rate.     

狭义相对论效应──运动时钟变慢的计算机模拟演示实验

利用精炼的C语言进行程序设计，定量模拟狭义相结论的运动时钟变慢，并对处于两种不同时空观的时钟运行进行对比，使得时间膨胀效应变得直观。     

MeV微集团束与物质的相互作用

简述了有关MeV微集团离子束与物质表面相互作用研究的概况．介绍了在北京大学技术物理系和重离子物理所１．７ＭＶ串列加速器上开展的有关实验研究及取得的初步结果． The recent development on investigation of MeV microcluster beam interaction with matter is outlined. And based on 5SDH 2 Pelletron of Peking University, some relative experimental results, such as identification and Rutherford backscattering measurement of MeV carbon cluster ions, stopping power of MeV silicon microcluster ions in Al film, damage producted in silicon by MeV silicon microcluster irradiation, etc. are briefly introduecd.     

Magnetic Properties of Hf0.8Ta0.2（Fe0.97A0.03）2 （A=Al, Co, Mn） Systems

Moessbauer studies on the effect of substitution with 3% Al, Co, Mn atoms in the intermetallic compound of Hf0.8Ta0.2Fe2 are reported. The Al substitution leads to increase of the FM-AFM transition temperature and to decrease of the AFM-PM transition temperature. The Co substitution leads to disappearance of the FM state, only showing some FM impurity component, while Mn substituted compound indicates coexistence of FM and AFM states at low temperature. The phenomena imply complex itinerant electron properties in these magnetic systems.     

Construction of 2Ⅲ^[m-（m-k）] Designs with the Maximum Number of Clear Two-factor Interactions

It is useful to know the maximum number of clear two-factor interactions in a_Ⅲ~(m-(m-k))design.This paper provides a method to construct a 2_Ⅲ~(m-(m-k))design with the maximum number of clear two-factorinteractions.And it is proved that the resulting designs have more clear two-factor interactions than thoseconstructed by Tang et al.Moreover,the designs constructed are shown to have concise grid representations.     

Average Property of Isospin Effects Induced by Neutron-Halo Nuclei

We study the average property of the isospin effects of reaction mechanism induced by neutron-halo nuclei within the isospin-dependent quantum molecular dynamics model. We find that the extended neutron density distribution for the neutron-halo projectile brings an important isospin effect into the reaction mechanism, which induces the decrease of nuclear stopping R; however, it induces the obvious increases of the neutron-proton ratio of nucleon emissions （n/p）nucl for all of the beam energies in this work, compared to the same mass stable colliding system.     

聚偏氟乙烯辐射效应的研究——II.晶区辐射损伤点的研究

研究了聚偏氟乙烯 (PVDF)晶体结构与辐射效应的关系 .利用不同的热处理条件 ,获得了 7种不同规整性、不同结晶度的样品 ;通过对其辐射效应的研究 ,探讨了材料结晶区和晶区内不同部位的辐射效应以及这些不同的结构对材料辐射效应的影响 .使用示差扫描量热分析 (DSC)测量样品零熵产生相变温度、结晶度等随吸收剂量的改变 ,以及不同退火条件样品的辐射效应 .讨论了PVDF样品晶体辐射损伤与样品结构的关系 .利用电子自旋共振谱仪 (ESR)测量不同辐照后样品残余自由基的浓度及这些残余自由基加热条件下的不同命运 .结合DSC分析及X射线衍射分析得到晶体辐射损伤是从晶体表面折叠圈区和晶体茎杆内部缺陷区同时开始的结论