SQUEEZING PROPERTIES OF THE RADIATION FIELD IN THE INTERACTION OF SQUEEZED VACUUM WITH TWO TWO-LEVEL ATOMS THROUGH TWO-PHOTON TRANSITION

We study the squeezing and the amplitude-squared squeezing of radiation field in the interaction of squeezed vacuum state with two two-level atoms, and discuss the effects of the relative value of two atom-field coupling constants on them. The numerical results show that the presence of one additional atom introduces noatrivival cooperative effects into the squeezing and the amplitude-squared squeezing of radiation field.     

双模腔场－两原子系统中原子和场的动力学特性

研究了关联双模ＳＵ（１，１）相干态与两个二能级原子的相互作用过程中原子的崩溃与回复效应、辐射场的双模压缩和高阶双模压缩、以及光场的两模之间的非经典相关性质，详细讨论了原子间的偶极相互作用对它们的影响。     

原子间的偶极相互作用对真空态T－C模型中场的非经典性的影响

本文研究了原子间的偶极－偶极力对真空态单光子Ｔａｖｉｓ－Ｃｕｍｍｉｎｇｓ模型中辐射场的非经典效应的影响。     

两原子非简并双光子Jaynes-Cummings模型的辐射谱

本文研究了两原子非简并双光子Jaynes-Cummings模型的辐射谱,结果表明,当双模腔场处于不同数态时,辐射谱呈现如下新特性:当一腔场处于真空态,另一腔场为强场时,辐射谱为对称六峰结构,任两对称峰的间距均与√2n₂g成正比;当双模腔场均为强场时,辐射谱为对称四峰结构,两内峰的间距(4g)与数态光子数n₁及n₂无关;当一腔场处于真空态,另一腔场处于数态|n₂>时,辐射谱一般为对称六峰结构,当n₂=1时,谱变为对称四峰结构。     

P6（D6h）和P12（D6h的从头算研究

利用Ｇａｕｓｓｉａｎ－９２从头算程序，在６－３１Ｇ￣＊基组下优化Ｐ_６（Ｄ_６ｈ）分子和Ｐ_（１２）（Ｄ_（６ｈ））原子簇，并进行了振动频率的计算．得到２Ｐ_６（Ｄ_（６ｈ））→Ｐ_（１２）（Ｄ_（６ｈ））总能量的相对值，即△Ｅ＝Ｅ_Ｐ_（１２_（Ｄ_（６ｈ））－２ＥＰ_６（Ｄ_（６ｈ））＝－１．１９７ｅＶ．　Ｐ_（１２）（Ｄ_（６ｈ））原子簇较２Ｐ_６（Ｄ_（６ｈ））分子在热力学上更为稳定。基组下，Ｈｐ＝ＨＰ优化的Ｐ＝Ｐ双键键长为０．２００５ｎｍ，Ｈ２Ｐ─ＰＨ２优化的Ｐ─Ｐ单键键长为０．２２１４ｎｍ，显然，Ｐ６（Ｄ６ｈ）分子中的键长比优化双键长０．００９１ｎｍ，比优化单键短０．０１１８ｎｍ，对于Ｐ６（Ｄ６ｈ）分子而言，其键长介于单、双键之间且相等。Ｐ６分子前线轨道的第３９条分子轨道形式估算为：联系人及第一作者：冯健男，男，２５岁，博士研究生。     

冯晖墓壁画颜料的高分辨电镜和拉曼光谱分析

利用高分辨率电镜(HREM)和拉曼光谱等方法,对五代冯晖墓内壁画不同颜料的结构与成分进行了分析。结果表明,红色、黄色、黑色等矿物颜料保存都较为完好,未发生显著的变化,这为以后壁画保护方案的确立提供了科学依据、同时也证明,在样品量极少的情况下,利用高分辨电镜和拉曼光谱等方法可有效鉴别古代无机颜料的种类。     

Three-axis magnetic flux leakage in-line inspection simulation based on finite-element analysis

With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage (MFL) in-line inspection system is introduced first. Besides, a mathematic model of the system according to the ampere circuit rule, flux continuity theorem, and column coordinate transform is built, and the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and design the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time, so we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhances the detection ability to different types of defects but also improves the precision and reliability of the inspection system.     

基于群集理论的高阶对称结构可动性判定

基于群集理论,对由转动副及刚性连杆单元构成的高阶对称过约束体系进行了可动性分析。由于该类结构不同于铰接杆系结构,且自应力模数较高,很难用常规可动性判定方法来研究结构的几何稳定性。本文首先从单根单元的广义力平衡方程出发,建立了整体结构的平衡矩阵及位移协调矩阵,并从其零空间分别得到了机构位移模数及自应力模数。随后,根据对称群的不可约子空间及特征标,得到了位移模数及自应力模数的对称表示,从而根据二者的对称属性判定结构的可动性。算例结果表明,本文所述方法合理可行,且讨论的三个高阶对称结构皆被证明是单自由度可动的。     

目标表面可见光谱BRDF的实验测量及优化建模

介绍了一种用双向反射分布函数测定仪进行目标双向反射分布函数测量的方法。运用该测量系统在可见光谱区域对样片进行了实验测量,然后对BRDF实验数据进行谱积分预处理,结合BRDF五参数半经验统计模型,利用遗传模拟退火算法,获取样片的BRDF模型参数,并获得了三维空间的BRDF分布。结果表明,获得的可见光谱BRDF模型能准确反映材料的光散射特性,符合工程要求。     

与原子依赖强度耦合双模压缩真空态的量子纠缠

在考虑原子与双模光场依赖强度耦合双光子共振相互作用的条件下,应用量子相对熵研究了双模压缩真空场模间纠缠度的演化.结果表明,在原子与光场相互作用之后,模间纠缠度作周期性的变化.在强场条件下,模间纠缠度总是在初始时刻达到最大值,其变化幅度基本保持不变.在初始场很弱的条件下,纠缠度演化的特点与原子初始状态有关,当原子处于激发态和基态的等概率叠加态时,纠缠度变化的幅度最大.控制原子与光场的作用时间及原子的初态,可以调整双模光场间的纠缠.