Quantum entanglement in the mode-mode competition system

Considering a two-level atom interacting with the competing two-mode field, this paper investigates the entanglement between the two-level atom and the two-mode field by using the quantum reduced entropy, and that between the two-mode field by using the quantum relative entropy of entanglement. It shows that the two kinds of entanglement are dependent on the relative coupling strength of atom-field and the atomic distribution, and exhibit the periodical evolution. The maximal atom-field entanglement state can be prepared via the appropriate selection of system parameters and interaction time.     

Analytic equation of state for solids with multi-exponential potential based on analytic mean field potential approach and applied to the epsilon phase of solid oxygen

The thermodynamic properties of the ε phase of solid oxygen are studied by using the analytic mean field approach （AMFP）. Analytic expressions for the Helmholtz free energy, internal energy and equation of state of solid oxygen have been derived based on the multi-exponential potential. The formulism for the case of double-exponential （DE） model is applied to the ε phase of solid oxygen. Its four potential parameters are determined through fitting the experimental compression data of the ε phase of solid oxygen. Numerical results of the pressure dependence of the volume calculated by using the AMFP are in good agreement with the original experimental data. This suggests that the AMFP is a useful approach to study the thermodynamic properties of the ε phase of solid oxygen. Furthermore, we predict the variation of the volume, lattice parameters and intermolecular distances with pressure, and some thermodynamic quantities versus volume, at several higher temperatures.     

自喇曼散射及二阶色散系数对三阶飞秒孤子的影响

介绍了分步傅里叶数值方法的原理和步骤。通过数值模拟，得到随着自喇曼散射系数的增大，三阶飞秒孤子分裂的两个孤峰，左峰的超前越来越小，而右峰的延迟越来越大。从频谱上看，开始蓝移随着自喇曼散射系数的增大而增大，当增大到一定程度时，两边的频谱会中移。增加二阶色散系数，三阶飞秒孤子的裂化也会得到控制，在频域内表现为频谱中移变窄。     

Dynamics of cooperative emissions in a cascade three-level molecular system driven by an ultrashort laser pulse

This paper investigates the dynamics of cooperative emissions in a cascade three-level system driven by an ultra, short laser pulse by solving numerically the full-wave Maxwell-Bloch equations. The 4, 4＇-bis（dimethylamino） stilbene molecule is used as the model molecule because of its strong two-photon absorption property. The two-colour cooperative emissions are studied as functions of molecular number density and dephasing rate of the dipole coherence. The propagation effects on the evolution of the cooperative radiations are also taken into account. The cooperative radiations are enhanced for large number density of the molecule, while the fast dephasing of the dipole coherence reduces the intensity of the cooperative radiations and delays the emission times or even inhibits the formation of the emissions. The delay time of the radiation decreases with the increase of the molecular number density and the propagation distance.     

利用数值模拟测量闪光照相中的H-D曲线

H-D曲线表明了照射量与底片光学密度之间的关系，是定量提取客体信息的基础。尽管实验上提出了许多测量“屏-片”的H—D曲线的方法，但这些方法所采用的实验布局与实际照相环境存在一定的差异。第一，许多实验采用的光源是单能源（如^60Co），没有体现底片系统对不同X射线能量的响应特性；第二，实验装置与实际照相模型存在比较大的差异，由于光子能谱和角分布以及散射的影响，测量的H-D曲线往往很难用到实际照相中；第三，也是更重要的一点是目前测量高能X射线照射量的仪器的测量误差较大，     

杂交有限元的区域分解法

近几年来,由于并行计算机的迅速发展,求解椭圆型微分方程的区城分解法又引起了人们的重视.这一方法的基本思想是把求解区域分解成许多子区域,每个子区域上用一台计算机求解.这种方法适应并行机的需要,是用并行机解大型椭圆型偏微分方程的一     

闪光照相中源尺寸和散射对成像的影响

 利用Monte Carlo(MC)模拟技术解释实验中心线灰度曲线的各部分波形。结果发现，系统中的散射照射量、光源的尺寸和H-D特征曲线的形状对实验灰度曲线的各部分波形均有影响：散射量越大，中心信号幅度越低;H-D曲线趾部的非线性越严重，中心信号幅度也越低;光源尺寸造成图像越模糊。指出了用实验波形可以半定量确定系统散射程度和光源尺寸。在测量照射量时，应该尽可能避免散射的干扰,用台阶法测量H-D曲线时，应使台阶远离剂量片而前移。     

高聚物PMMA的受力变形行为与粘弹－塑性本构理论模型

对高聚物ＰＭＭＡ实验测定了不同（Ｔ，ε）的单轴加卸载循环的应力－应变曲线。讨论了应力促进热激活塑性变形的活化粘壶理论和塑性变形的发展规律。提出由ＳＬＳ或ＭＳ与活化粘壶作串联耦合的粘弹－塑性本构理论模型，给出了微分和积分形式的本构方程组，用于拟合求解加卸载循环的应力－应变曲线，获得良好吻合的结果。详细讨论了ＰＭＭＡ在加载过程中的受力变形行为，包括起始加载的粘弹性变形，ε＿ｖ和ε＿ｐ的互相挤占，屈服点，以及屈服后应变软化和硬化的抗衡过程。对应变软化－硬化效应提出一种新的起因于粘弹变形内禀滞后效应的理论解释，并定名为粘弹软化－强化效应。对所包含的粘弹变形成分，从Ｅ＿ｖ的移位因子和归一化应力－应变主曲线两方面，讨论了可能存在的率温等效关系。     

环上矩阵的Moore-Penrose逆的注记

讨论带有对合反自同构的环上矩阵的广义逆,给出了矩阵存在Mooore－Penrose逆的条件及Moore－Penrose逆的一些性质和显式．     

一类三阶自治系统的积分法

研究一类三阶自治系统的积分方法,证明了在一定条件下,这类系统的积分问题归结为求解由该方程的系数所确定的Riccati方程