基于微观IBM对电子-核散射及核电磁性质的研究(I) BE理论方案

从价核子自由度出发构造出核跃迁电荷/电流密度算符,采用Dyson玻色子展开技术给出了获取核玻色子形式跃迁电荷/电流密度有效算符的一种微观方法(BE方法).利用微观相互作用玻色子模型(IBM)提供的波函数可在玻色子态空间中求出核跃迁电荷/电流密度,结合电子-核散射以及核电磁跃迁的形式理论,建立了可研究电子-核散射各种形状因子,微分散射截面以及核约化跃迁几率、电磁多极矩、核态g因子等物理量的理论方案.在一种微观sdIBM-2框架下,结合现有理论方案,初步计算了     

Inversion of an Atomic Wave Packet in a Circularly Polarized Electromagnetic Wave

We study behavior of an atomic wave packet in a circularly polarized electromagnetic wave,and particularly calculate the atomic inversion of the wave packet.A general method of calculation is presented.The results are interesting.For example,if the wave packet is very narrow or /and the interaction is very strong,no matter the atom is initially in its ground state or excited state,the atomic inversion approaches zero as time approaches infinity.If the atom is initially in its ground state and excited state with the probability 1/2 respectively,and if the momentum density is an even function,then the atomic inversion equals zero at any time.     

模糊互补判断矩阵的相容性及一致性研究

给出了模糊互补判断矩阵的相容性，权重矩阵等概念，对模糊互补判断矩阵的相容性和一致性详细地进行了研究，证明了在模糊互补判断矩阵Ai(i=1,2,…,s)是一致性可接受的情况下，它们的综合判断矩阵也是一致性可接受的，从而为模糊互补判断矩阵在决策领域中的广泛应用奠定了理论基础。     

电磁场数值分析的无单元Galerkin方法

阐述了移动最小二乘无单元Galerkin方法的基本原理及实现过程,给出了权函数的选取原则,和基于Lagrange乘子法的边界条件处理方法,结合算例说明了该方法用于电磁场分析的有效性和计算特点,并着重研究了影响半径对计算结果的影响,计算结果表明,对于非均匀媒质,影响半径应在一个与高斯积分点有关的范围内取值,以避免媒质作用的“扩散”而降低计算精度。     

电磁干扰下时间分辨测量系统信号外触发技术

在实验的基础上给出了束参数时间分辨测量系统的实验布局和特点,分析高压电磁干扰对直线感应加速器中时间分辨测量系统外触发性能的影响和变化规律;进一步探讨系统高压电磁干扰后的抑制措施。针对电磁空间干扰情况,主要通过采用光纤传输控制信号的措施,能很好地传输窄脉冲,信号延时抖动小于2ns,达到了高速信号的可靠传输要求,采用嵌入式控制器既解决了抗电磁干扰的要求,也满足了束参数时间分辨测量系统的使用要求。     

有限口径非周期亚波长衍射聚焦偏转器的严格矢量优化

有限口径非周期亚波长衍射光学器件的亚波长结构特性使得传统标量衍射理论失效,必须借助严格电磁理论进行器件的设计。提出一种循环平面波谱算法(IterativePlaneWaveSpectrumAlgorithm,IPWSA)作为器件优化算法,利用二维时域有限差分方法作为严格电磁计算模式,根据Farn方法对器件面型进行亚波长处理,设计出有限口径非周期具有亚波长结构的衍射聚焦偏转器件,偏转角为24.8°,该器件可与激光器集成构成微型集成光学系统,也可以用在红外量子阱系统中。详细分析了算法原理,设计实例验证了算法的优化效果。     

Green＇s function formalism in semi-infinite composites： an investigation of local field distribution

In the resonant composites, the formerly developed Green's function formalism (GFF) can be used to compute the local field distribution near resonance. In this paper, we extend the GFF in the infinite network to the semi-infinite networks by the method of image. Using the formalism, we investigate the local field distribution near resonance for the impurity clusters with admittance ε_0 embedded in one semi-infinite network with ε_1. With varying the admittance ε_2 of another semi-infinite network, we find that the local fields in the boundary experience great changes, especially at ε_2=-ε_1. The existence of the boundary enhances the localization of the fields within and around the metallic clusters. Therefore, the intensity of local field is influenced by the arrangement of impurity metallic bonds and its distance from the boundary.     

二维介质型光子晶体的直线法分析

运用直线法对二维介质型光子晶体的能带结构进行分析,给出直线法中关于二维介质型光子晶体的本征方程的建立过程.同时,对不同参数的光子晶体进行计算,计算结果通过时域有限差分算法(FDTD)及已发表的数据得到了验证,并考虑不同结构的光子晶体的TE波与TM波的带隙形成情况,可为二维介质型光子晶体的设计提供参考.     

Evolution of the N = 20 and N = 28 shell closures in neutron-rich nuclei

The isospin dependence of shell closure phenomena is studied for light neutron-rich nuclei within a microscopic self-consistent approach using the Gogny force. Introducing configuration mixing, ³²Mg is found to be dynamically deformed, although the N = 20 spherical shell closure persists at the mean-field level for all N = 20 isotones. In contrast, the N = 28 spherical shell closure is found to disappear for N - Z≥ 10 whereas deformed shell closures are preserved and lead to shape coexistence in ⁴⁴ S. Configuration mixing shows that the ground state of this nucleus is triaxially deformed. The first 2⁺ excitation energy E_x = 1.46 MeV and the reduced transition probability B(E2;0⁺ _gs→ 2⁺ ₁)= 420 e ² fm ⁴ obtained with our approach are in good agreement with experimental data. Received: 26 July 2000 / Accepted: 30 August 2000     

一种时延范德波尔电磁系统中的复杂行为(Ⅱ)——时空混沌图案动态

对于一个由线性无损传输线加非线性边界条件组成的简单无穷维电磁系统，应用行波理论确定了电压反射波的局部映射关系.数值仿真结果表明，当系统参数发生变化时，传输线沿线电压存在着非常丰富的时空非线性现象.通过描绘出空间振幅变化图和时空行为发展图，定性分析了传输线沿线电压的时空混沌图案动态，为研究和理解时空混沌提供了一种良好的可求解模型. 关键词： 图案 时空混沌 无穷维系统 时延范德波尔电磁系统