The axiom of choice holds iff maximal closed filters exist

It is shown that in ZF set theory the axiom of choice holds iff every non empty topological space has a maximal closed filter.     

《阿贝成像与空间滤波》多媒体课件制作

本介绍应用多媒体创作工具和三维动画设计软件制作《阿贝成像与空间滤波》多媒体课件的方法，介绍了课件制作的关键技术。课件内容可用于光学工程、光信息科学技术、电子科学技术类专业高年级学生的实验教学。     

高温超导微带线滤波器的精确设计方法探讨

文中对高温超导微带线滤波器的精确设计方法进行了探讨 ,以 GSM180 0移动通信基站用高温超导带通滤波器为例进行了设计、模拟和优化。滤波器选用平行耦合型发夹式微带线结构 ,中心频率 174 7.5 MHz,通带带宽 75 MHz。模拟结果表明 :该滤波器具有良好的频响特性 ,带内波纹 <0 .1d B,反射损耗 >15 d B,基本符合设计要求     

一种结构新颖的高温超导群时延均衡器

本文提出一种平面微带型高温超导微波群时延均衡器，它是由一个3dB混合耦合器和两个单端口反射滤波器构成的全通网络．该群时延均衡器能与不同类型超导微带滤波器级联，实现相位均衡，减小相位失真，改善接收机前端信号群时延特性，提高通信质量．     

Comparison of the Kalman filter and dedicated algorithms for processing data for solution equilibria,noise smoothing and calibration

The suitability of the Kalman filter for extracting acidity (protonation) constants from titration curves, for noise removal, and for multicomponent determinations in the presence of sample-related interferences is described. The performance of the algorithm is illustrated with simulated examples and checked by comparing the results with those obtained by dedicated methods (Savitzky-Golay and Fourier-transform procedures and the general standard-addition procedure). The ability of a combination of two Kalman filters as a fixed-interval smoother for noise removal is stressed.     

高反射浅光栅的偏振特性研究及其在双折射滤光片中的应用

用瑞利-傅里叶(Rayleigh-Fourier)数值方法及椭偏测量,研究了高反射正弦形浅光栅的偏振特性.当正向入射条件下,光栅周期与波长之比满足某一关系时,其反射光电场的两垂直方向分量相移差大的特性,制成了一种新颖的双折射滤光片,文中给出了这种双折射滤光片的初步实验结果.     

倍频式振动合成信号源研制

利用倍频电路产生十路不同频率的相干信号，通过滤波、移相、幅度调整、加法器、乘法器等电路可实现用多路正弦信号做波形合成、两路信号的同向振动合成，李萨茹图形、调幅波等实验及演示。     

密集型波分复用薄膜干涉滤光片的设计

介绍了波分复用系统对薄膜干涉滤光片的基本要求，为了满足这些要求，一方面需要精心选择基板和薄膜材料，另一方面要寻找性能优良，制造容易的膜系，文中提出了二种适宜于设计这种滤光片的方法。     

Numerical Study on Efficient Optical Switching Based on the Nonlinear Phenomenon in a Guided-Mode Resonant Grating with Kerr Medium

Optical switching in a guided-mode resonant grating (GMRG) with a Kerr medium was numerically simulated by the nonlinear finite differential time domain (FDTD) method. The asymmetric resonant grating was adopted to have two resonant reflection peaks for the pump light and the probe light. When the pump light had a wavelength which was slightly longer than the resonant wavelength, the light was suddenly enhanced at a certain intensity because of the nonlinear resonance phenomenon. This resonance is effective in reducing the pump intensity for optical switching. When we assumed the resonant grating of polydiacetylene toluene sulphonate (PTS) with a linear refractive index of 1.88, a third-order susceptibility of 8.5 × 10⊃−0 esu and Q factors of resonant reflection which were ∼800, the pump light of 15 kW/mm⊃ changed transmittance of the probe light from 0 to 80%. 2005 The Optical Society of Japan