受扰陆上级联掺铒光纤放大器系统的特性分析

通过引入描述扰动程度的参数X和描述掺饵光纤放大器(EDFA)饱和特性陡度的参数T,本文推出了一个归一化的EDFA增益表达式,并据此对系统受扰后的信号恢复特性和误码率变化进行了分析。结果表明：对EDFA饱和程度较浅的陆上光纤通信系统,出现小于1dB(X≥0.8)的微扰时,光功率经一级EDFA即可恢复其原值的90%;系统经3dB扰动(X=0.5)后,光功率(信号和噪音功率之和)经过三级EDFA方能恢复到原值的90%,但系统误码率(BER)的恶化则在两个量级以上,且随着扰动开始点的后移而更加恶化。这说明为保证系统受扰后能正常工作,其光信噪比应有相当大的裕量。EDFA饱和越浅,系统受扰动的影响就越严重。     

层结流体中在热外源和β效应地形效应作用下的非线性Rossby孤立波和非齐次Schrödinger方程

在层结流体中, 从带有地形、热外源耗散的下边界条件以及带有热外源的准地转位涡方程开始, 使用小参数展开方法和多尺度时空伸长变换推导出了具有热外源、β效应和地形效应的强迫Rossby孤立波方程, 得到孤立Rossby振幅满足的带有地形与热外源的非齐次非线性的Schrödinger方程. 通过分析Rossby孤立波振幅的变化, 指出了热外源、β效应和地形效应都是诱导Rossby孤立波产生的重要因素, 给出了切变基本流下地形、热外源和层结流体中Rossby的相互作用.     

人口生育率双向极限

本文给出了妇女总和生育率双向极限的精确估计,证明了双向极限上、下界的基本定理,提出了总和生育率上极限和下极限的表达形式.按照这些估计式,根据实际统计数据,计算了包括我国在内的世界上46个国家的总和生育率双向极限估计.在此基础上划分了人口发展的正增长、负增长和零增长三种类型.这些结果不仅在理论上,而且在实践中对掌握人口发展趋势和控制人口增长具有重要意义.     

DOUBLE-EDGED LIMIT OF TOTAL FERTILITY RATES

In this paper we present the accurate estimation of total fertility rates, prove the theorem of upper and lower bounds of double-edged limit and provide the formulas of upper and lower bounds of total fertility rates. Based on these estimations and statistical data, we calculate the upper and lower bounds of the double-edged limit for 46 countries including China. Furthermore, we describe the positive growth rate, negative growth rate and zero growth rate of population development. These results are of great importance for us to control population not only in theory but also in practice.     

Heterogeneous anisotropic complex structure gradual model and constitutive relation

Four new gradually delaminate models of the three-dimensional macro-/mesoscopic structure and delamination of the heterogeneous anisotropic composite (HAC) are set up by conducting research into its structure and performance. A general theory, which demonstrates the three-dimensional constitutive relation of the macro-/mesoscopic performance of this structure is further developed. The macroscopic expression of HAC is presented in terms of a Tanigawa delaminate homogeneous equivalent approach, the mesoscopic problems are analysed utilizing Eshelby－Mori－Tanaka theory, with the introduction of the representative volume elements of monolayer single unit cell and interlaminar double unit cells. According to the gradual continuity of the structure as a whole, great attention is given to the modelling and research of the interlaminar macroscopic and mesoscopic problems of HAC structure. Comparison with the existing solutions is made through calculation of typical cases.     

缓变下垫面和耗散作用的非线性Rossby波

从准地转位涡方程出发,采用摄动方法和时空伸长变换推导了在缓变下垫面和耗散共同作用的Rossby代数孤立波方程,得到Rossby波振幅满足带有缓变下垫面的非齐次Benjamin-Davis-Ono-Burgers(BDOBurgers)方程的结论.指出地形效应和耗散是诱导非线性Rossby波产生的重要因素,说明了在缓变下垫面强迫效应和非线性作用相平衡的假定下,Rossby孤立波振幅的演变满足非齐次BDO-Burgers方程,给出在切变基本气流下缓变下垫面和正压流体中Rossby波的相互作用.     

SPECTRAL PROPERTIES OF POPULATION OPERATOR AND ASYMTOTIC BEHAVIOUR OF POPULATION SEMIGROUP

In this paper we discuss the spectral properties of the Population operator, prove that the population operator has only one real eigenvalue γ_0, which is greater that real parts of other eigenvalues,and find the corresponding relation between γ_0 and the critical fertility rate β_(cr). We also study the existence and asymptotic behaviour of the semigroup for the population system, then come to the conclusion about the stability of the population system,including the existene of the steaby population state in the critical case of the fertility rate.These are all the new results of the quantitative population theory.     

分层数对Q235钢薄板抗侵彻性能的影响

利用轻气炮进行卵形头、平头以及半球形头杆弹正撞击等厚接触式叠层靶实验,得到这3种结构的初始速度-剩余速度曲线以及弹道极限,对回收靶体进行分析,研究分层数对叠层靶抗侵彻性能和失效模式的影响。结果表明:对于延性金属薄板,分层结构降低靶体的弹道极限,单层板的抗侵彻性能高于叠层板的抗侵彻性能。对于平头弹和卵形头弹,弹道极限随分层数的增加而降低;对于半球形头弹,弹道极限随分层数的增加先降低后升高;分层数对弹道极限的影响随弹体初始撞击速度的增加而减小。     

切变纬向流中β效应与缓变地形Rossby波

正压流体中,从有外源的准地转位涡方程出发,采用摄动方法和时空伸长变换推导了具有β效应、缓变地形和外源的Rossby孤立波方程,得到Rossby波振幅满足带有缓变地形与外源强迫的非齐次mKdV-Burgers方程的结论.通过分析孤立Rossby波振幅的演变,指出了β效应、地形效应以及外源都是诱导Rossby孤立波产生的重要因素;说明了在缓变地形强迫效应和非线性作用相平衡的假定下,Rossby孤立波振幅的演变满足非齐次mKdV-Burgers方程;给出在切变基本气流下缓变地形和正压流体中Rossby波的相互作用关系.