三包层WⅠ和WⅡ型单模光纤波导色散特性的研究

研究了三包层WⅠ和WⅡ型单模光纤的波导色散特性。结果发现在相同条件下，三包层WⅠ和WⅡ型单模光纤零色散点的调节范围比传统的双包层W型单模光纤明显增大。详细分析了几何参量P、Q和光学参量R1、R2对单模传输时的波导色散特性和低次模截止频率的影响。所得的研究结果为获得更为理想的色散补偿、色散平坦光纤及设计新型无源光器件提供了重要的依据。计算波导色散的方法可推广到多包层光纤。     

Nonparametric estimation and adaptive control in a class of finite Markov decision chains

We consider a class of Markov decision processes withfinite state and action spaces which, essentially, is determined by the following condition: The state space isirreducible under the action of any stationary policy. However, except by this restriction, the transition law iscompletely unknown to the controller. In this context, we find a set of policies under which thefrequency estimators of the transition law are strongly consistent and then, this result is applied to constructadaptive asymptotically discount-optimal policies.Dedicated to Professor Truman O. Lewis, on the occasion of his sixtieth birthdayThis research was supported in part by the Third World Academy of Sciences (TWAS) under Grant TWAS RG MP 898-152, and in part by the Consejo Nacional de Ciencia y Tecnología (CONACYT) under Grant A128CCOEO550 (MT-2).     

无线电波透视法及其应用

无线电波透视法是利用无线电波在钻孔中的发射和接收来确定地下介质特性和地质构造的一种物探方法，当电磁波在地下有耗介质中传播时，遇到岩性不同的分界面就会产生不同的电磁波反射，折射，透射和频散，吸收等，通过研究接收到的电磁波的性质达到探测地下目标物的目的，本文简述了该方法的理论，描述了方法的分类，概述了目前使用的发射天线，接收天线和常用的仪器，总结了野外工作方法和解释方法，最后给出了应用实例说明其应用效果。     

Charge density fluctuation of low frequency in a dusty plasma

The charge density fluctuation of low frequency in a dusty plasma, which is derived from the longitudinal dielectric permittivity of the dusty plasma, has been studied by kinetic theory. The results show that theP value, which describes the relative charge density on the dust in the plasma, and the charging frequency of a dust particle Ω _c , which describes the ratio of charge changing of the dust particles, determine the character of the charge density fluctuation of low frequency. For a dusty plasma ofP≪1, when the charging frequency Ω _c , is much smaller than the dusty plasma frequency ω_d, there is a strong charge density fluctuation which is of character of dust acoustic eigenwave. For a dusty plasma ofP≫1, when the frequency Ω _c , is much larger than ω _d there are weaker fluctuations with a wide spectrum. The results have been applied to the ionosphere and the range of radius and density of dust particles is found, where a strong charge density fluctuation of low frequency should exist.     

（NPX2）3（X=F,Cl,Br,I）的几何构型和振动频率的MNDO研究

运用ＭＮＤＯ方法对标题化合物的几何构型和振动频率进行了理论计算，计算出来的结构参数与晶体Ｘ－射线实验数据一致；计算出来的捱劝频率与红外和拉曼光谱基本一致，最后，计算得出目前在实验上尚未报道的（ＮＰＩ２）３的上述两个方面的理论数据。     

单模光纤中皮秒啁啾脉冲压缩

对单模光纤正群速色散区秒啁啾脉冲的非线性传进行了近似的解析分析和定量的数值计算。结果表明，负啁啾脉冲在传输过程中能得到有效压缩。压缩比与脉冲初始峰值功率和初始啁啾程度有关。初始峰值功率一定的脉冲，其压缩比随初始啁啾程度的增大面大，初始啁啾程度一定的脉冲，压缩比随初始峰值功率的增大而减小，表明自相位调制效应导致脉冲压缩效果变差。计算结果还表明，在脉冲时域宽度得到压缩的同时，光谱宽度也能得到同步压缩。     

用频域法实现圆环形目标物的计数

研究了用频域法实现圆环形目标物计数的方法。对空域中含有圆环形目标物的二值图像，经傅里叶变换后在频域内进行滤波，再经傅里叶反变换后取一阈值进行处理，则对应于圆环形目标物即变为一个实心体，然后对实心体进行计数即可实现对圆环形目标物的计数。对该方法进行了数学描述，并分别用模拟图像和实际图像进行了实验。结果表明，该方法消除噪声的效果好，对部分封闭圆的检测同样有效，且可用于目标物有粘连的情况。该方法对圆环形目标物的尺寸相差不大的情况更为有效。     

一种新型的数字编码轨道电路

基于现有UM71无绝缘轨道电路的传输通道,讨论了各种传输方案,提出了一种采用模拟调频方式的32位数字编码轨道电路,选用TMS320C32作为CPU,设计了发送和接收子系统,最后给出了室内仿真试验及其结果.     

万用表检测电容器方法分析及改进

本文从教学实验的实践出发,对使用万用表测量电容器容量的方法进行了分析,并对电路进行了一定改进。