相空间中二阶线性非完整系统的形式不变性

研究相空间中二阶线性非完整系统的形式不变性.给出相空间中二阶线性非完整系统形式不变性的定义和判据，得到形式不变性的结构方程和守恒量的形式，并举例说明结果的应用. 关键词： 相空间 二阶线性非完整系统 形式不变性 守恒量     

单相磁电多铁性体研究进展

文章从电磁耦合现象及磁电效应出发,简要介绍了单相磁电多铁性体(铁电磁体)的最新研究进展。     

Dicke超辐射系统多光子过程中光场的压缩效应

本文利用微扰技术研究了与Ｄｉｃｋｅ模型中Ｎ个两能级原子系统通过多光子过程相互作用的相干态场的时间演化．研究表明，若多光子Ｄｉｃｋｅ模型中的Ｎ个两能级原子初始时皆处于去激发状态，则在短时近似下光场可存在二阶压缩效应．     

世界何处没有磁

 在一般人看来,磁是一种少见的现象,似乎只有磁石吸铁和指南针指南等少数现象才同磁有关,其他许多现象都与磁无关,看作是无磁的或非磁的。实际上,这样的看法是不对的。因为现代科学的发展,已经认识到,磁是普遍存在的,磁与我们的关系是十分密切的。为什么这样说?因为所谓磁,是指物质的磁性和空间的磁场。磁性是指物质在磁场中会受到力或力矩作用的性质,磁场是指运动的电荷在其中会受到力作用的物理场。从这样的意义看,任何物质都是具有磁性的,只有强弱的差别;任何空间都是存在磁场的,只有高低的不同。现在让我们来看一看,世界何处没有磁?     

Effect of the Coadsorption of CO and O2 on the Phase Diagram of the Ziff—Gulari—Barshad Model

The effect of the coadsorption of CO and O2 on the Ziff-Gulari-Barshad surface catalytic reaction system in studied by Monte Carlo simulation.The coadsorption of both species adds an extra reaction step to the classical Ziff-Gulari-Barshad model.It is shown that the second-order phase transition from the reactive state to the O-passivated state in the Ziff-Gulari-Barshad model is eliminated,and the production rate of CO2 increases linearly along the fraction yco of CO in gas phase when it is low,in agreement with experimental results.We also find that the increase of the probability of the coadsorption leads to the decrease of the critical value of yco of the discontinuous phase transition to the CO-passivated state.     

利用Faraday效应的激光磁共振

本文叙述了在激光磁共振实验中,利用纵向磁光旋转效应-Famday效应来改善信噪比,并给出了这种方法的实验结果和理论分析.实验中,利用Faraday效应使信噪比改善约提高一个数量级.     

Electronic Transmission Properties of Two—Dimensional Quasi—Lattice

In the framework of the tight binding model,the electronic transmission properties of two-dimensional Penrose lattices with free boundary conditions are studied using the generalized eigenfunction method (Phys.Rev.B 60(1999)13 444).The electronic transmission coefficients for Penrose lattices with different sizes and widths are calculated,and the result shows strong energy dependence because of the quasiperiodic structure and quantum coherent effect.Around the Fermi level E=0,there is an energy region with zero transmission amplitudes,which suggests that the studied systems are insulating.The spatial distributions of several typical electronic states with different transmission coefficients are plotted to display the propagation process.     

Magnetostriction Dependence of the Relaxation Frequency in the Magnetoimpedance Effect for Amorphous and Nanocrystalline Ribbons

The magnetoimpedance effect and changes of the relaxation frequency fx are studied in CoFeSiB and CoFeMoSiB amorphous and FeCuNbSiB nanocrystalline ribbons.The evolution of the magnetostriction constant λs and relaxation frequency is analysed for the states with different magnetic anisotropies induced in the same ribbons.A monotonic decrease of the relaxation frequency is observed for shifting of λs towards positive values.