电磁感应双光子带隙的产生和控制

基于电磁感应透明技术, 通过求解原子的密度矩阵方程和电磁场的传输矩阵方程, 研究了被行波场和驻波场共同耦合的一个四能级冷原子介质的稳态光学特性, 发现在特定参数下能够产生一个几乎完美的双光子带隙结构, 在这两个光子带隙对应的频率区域内反射率都均匀地超过95%. 通过改变耦合场的强度和频率, 可以方便地调节这两个光子带隙的位置和宽度. 这一双光子带隙结构可用来实现全光路由和全光开关, 有望在全光信息网络中获得应用.     

Tb2Fe15.5Cr1.5化合物的本征磁致伸缩

通过x射线衍射及磁测量手段研究了Tb2 Fe1 5 5Cr1 5化合物的热膨胀性质及本征磁致伸缩性质 .研究结果表明Tb2 Fe1 5 5Cr1 5化合物在 2 93— 6 72K的温度范围内具有六角相的Th2 Ni1 7型结构 .在 4 32— 5 2 2K的温度范围内具有负热膨胀性质 ,其平均热膨胀系数 α =- 1 5 7× 10 - 5 K .对本征磁致伸缩的研究结果表明Tb2 Fe1 5 5Cr1 5化合物中存在着较强的各向异性的本征磁致伸缩 ,2 93K时其本征体磁致伸缩约为 8. 4× 10 - 3,晶格畸变主要发生在c轴方向上 .磁测量研究结果表明Tb2 Fe1 5 5Cr1 5化合物的居里温度约为 4 94K ,比其母合金Tb2 Fe1 7高约 80K .     

Study of sawtooth oscillations on the HT-7 tokamak using 2D tomography of soft x-ray signal

It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate twodimensional （2D） images of sawtooth oscillation on the HT-7 tokamak using the Fourier-Bessel harmonic reconstruction method, and using the singular value decomposition to analyse the data from soft x-ray cameras. By these two arrays, 2D image reconstruction of soft x-ray emissivity can be obtained without assumption of plasma rigid rotation. Tomographic reconstruction of the m=1 mode structure is obtained during the precursor oscillation of the sawtooth crash. The crescent-shaped mode structure appearing on the contour map of the soft x-ray emissivity is consistent with the quasiinterchange mode. The characteristics of the m=1/n=1 mode structure observed in the soft x-ray tomography are as follows： the magnetic surface is made up of the crescent-shaped “hot core” and the circular “cold bubble”. The structure of the magnetic surface rotates in the direction of the electron diamagnetic drift and the rotation frequency is the oscillation frequency of soft x-ray signals.     

The carbon impurity ohmic discharges on particle transport in the HT-7 tokamak

The line-integrated optical measurement of impurity radiation profiles for the study of light impurity transport is performed in the HT-7 tokamak. The carbon impurity line emissivity is obtained by Abel inversion. The radial transport behaviours of carbon impurities at different central line averaged electron densities ne are investigated in ohmic discharges. The diffusion coefficient Dk（r）, the convection velocity Wk（r） and the total flux of the impurity ions Fk decrease with the increase of ne, which shows a reduction in the impurity particle transport at higher electron densities.     

多壁碳纳米管膜湿敏特性的研究

研究了多壁碳纳米管(MWNTs)薄膜的湿敏特性，实验所用的多壁碳纳米管是用热灯丝化学气相沉积法(CVD)合成的.分别对未修饰和修饰的多壁碳纳米管膜温度和湿度特性进行研究后发现，修饰的多壁碳纳米管对温度和湿度非常敏感，且对湿度的响应时间和恢复时间短，重复性好.而未修饰的多壁碳纳米管对温度和湿度不太敏感.对修饰多壁碳纳米管的湿敏特性进行了理论分析，给出了其理论表示式. 关键词： 多壁碳纳米管 化学修饰 湿敏特性 物理吸附     

An Extended Model for Establishing Dominance in Multiattribute Decisionmaking

This paper is concerned with the use of incomplete information about utilities and weights in multiattribute decisionmaking. Because of time pressure and/or lack of knowledge, a decision maker may only be able to provide incomplete information which might be expressed as a set of linear inequalities. If the decision maker's information on both weights and utilities is imprecisely identified, then the model for establishing pairwise dominance becomes a non-linear program. A method for obtaining non-dominated alternatives without solving the non-linear program is proposed using a simple weighted-additive function.     

Three‐dimensional visible‐light capsule enclosing perfect supersized darkness via antiresolution

Supersized darkness in three dimensions surrounded by all light in free space is demonstrated theoretically and experimentally in the visible regime. The object staying in the darkness is similar to staying in an empty light capsule because light just bypasses it by resorting to destructive interference. A binary‐optical system is designed and fabricated based on achieving antiresolution (AR), by which electromagnetic energy flux avoids and bends smoothly around a nearly perfect darkness region. AR remains an unexplored topic hitherto, in contrast to the super‐resolution for realizing high spatial resolution. This novel scheme replies on smearing out the point spread function and thus poses less stringent limitations upon the object's size and position since the created dark (zero‐field) area reach 8 orders of magnitude larger than λ² in cross‐sectional size. It functions very well with arbitrarily polarized beams in three dimensions, which is also frequency scalable in the whole electromagnetic spectrum.     

光子晶体及其应用

光子晶体是８０年代末提出的新概念和新材料,文章简单回顾了光子晶体的历史,重点阐述了其主要特征以及可能的应用,同时论述了研究光子晶体的几种理论方法。     

一种利用激波进行落点测量的新方法

目前用于确定弹刃或导弹落点的声测方法多数是基于这样一个假定：其所发出的声波是一个平面波。但当其下落速度大于声速时,这个假定就不成立了,这时产生了一个锥面激波＾（４）,本文介绍了一种利用正方形基阵对其进行测量的方法。     

4f轨道的成键性质

本文介绍了目前国内外关于镧系配合物４ｆ轨道成键行为研究的现状与进展,对其理论和研究方法进行了系统的总结,归纳了４ｆ轨道的成键规律。