关于磁介质的抗磁性机理

本文从物理磁性的基本起源“分子电流”出发,通过分析电子在外磁场中的旋进,严格分析了磁介质的抗磁性的微观机理。     

MICRO-MOTION EFFECT OF A TRAPPED ULTRA-COLD ION IN A STANDING-WAVE LASER

In the absence of the requirements of the Lamb-Dicke limit and rotating wave approximation, we semi-classically investigate the dynamics of a trapped ultra-cold ion in the standing-wave laser, with the consideration of the time-dependent potential and pseudo-potential of the Paul trap. The specific calculations show that the larger the Lamb-Dicke parameter η and the Rabi frequency Ω, the greater the difference between the dynamics in the time-dependent potential and the pseudo-potential.     

锰/磷、钛/磷二元团簇的激光溅射产生与光解

利用激光溅射法直接产生了锰／磷、钛／磷二元团簇正、负离子MxPy^±(M=Mn、Ti） ,并用串级飞行时间质谱仪研究了团簇离子的组成与激光光解规律。实验表明钛与磷间成簇的能力强于锰与磷间成簇的能力,且MPy^+(M=Ti、Mn)团簇离子系列表现出峰强度了胡所含磷原子数目的奇偶性变化,这可能与P4结构的特殊稳定性有关。激光光解实验表明,失去中性P2、P4的通道为主要光解通道。随着团簇离子的生长,锰／磷团簇正离子逐渐由富磷簇向富金属簇过渡,钛／磷则趋向于形成钛原子数目与磷原子数目接近相等的团簇正离子,而二者与磷形成的团簇负离子MxPy^-(M=Mn、Ti) 逐渐趋向于x ≈ y,随样品中磷含量增加,锰／磷易形成富磷簇,钛／磷的组成趋向不改变。     

改进的Herriott型光学长程池

用凹面反射镜和平面反射镜组成结构简单、光路易调的光多次反射装置,计算了这种光学系统的稳定性条件。考察实际入射光束的直径和发射角,给出了最大反射次数的求法。制成适用于钛宝石激光光声光谱仪的光56次通过的长程池。理论计算的反射光斑分布与实验观测一致。这个技术有利于提高光声光谱和吸收光谱的探测灵敏度。     

平行平板间电流变液非零压力梯度Couette流动的稳定性分析

采用Rajagopal和Wineman所提出本构方程,对电流变液在二维平行平板间非零压力梯度Couette流动的线性稳定性问题进行研究。通过分析和数值计算发现,任何壁面运动都将使流动稳定性增强。在外加电场存在的情况下,电流变液效应也将使流动稳定性增强。     

Flow Injection Kinetic Spectrophotometric Determination of Cerium Based on the Decolorization Reaction Between Arsenazo III and Cerium (IV)

ABSTRACT

Trace amounts of cerium were analyzed by flow injection kinetic spectrophotometry, based on the decolorization reaction between arsenazo III and Ce(IV) in sulfuric acid medium at room temperature. The absorbance difference (ΔA) of decolorization was linear with the concentration of Ce(IV). The flow injection technique was used to precisely control the timing. Under the optimum conditions, the determination of Ce(IV) in the range 0.0–8.0 µg mL^?1 with a correlation coefficient (r) of 0.9982, the regression equation was ΔA = 0.0014 + 0.0406c (µg mL^?1). The detection limit (3σ) of 0.2 µg mL^?1 was achieved at a sampling frequency of 60 h^?1. The proposed method was applied to the analyses of Ce in soil successfully.     

Molecular constants of LiCl(X~1Σ~+) and elastic collisions of two ground-state Cl and Li atoms at low and ultralow temperatures

Interaction potentials for LiCl(X 1 Σ +) are constructed by the highly accurate valence internally contracted mul-tireference configuration interaction in combination with a number of large correlation-consistent basis sets,which are used to determine the spectroscopic parameters (D 0,D e,R e,ω e,ω e χ e,B e and α e).The potentials obtained at the basis sets,i.e.,aug-cc-pV5Z-JKFI for Cl and cc-pV5Z for Li,are selected to study the elastic collision properties of Li and Cl atoms at the impact energies from 1.0×10 12 to 1.0×10 4 a.u.The derived total elastic cross sections are very large and almost constant at ultralow temperatures,and their shapes are mainly dominated by the s-partial wave at very low impact energies.Only one shape resonance can be found in the total elastic cross sections over the present collision energy regime,which is rather strong and obviously broadened by the overlap contributions of the abundant resonances coming from various partial waves.Abundant resonances exist for the elastic partial-wave cross sections until l=22 partial waves.The vibrational manifolds of the LiCl(X 1 Σ +) molecule,which are predicted at the present level of theory and the basis sets cc-pV5Z for Li and the aug-cc-pV5Z-JKFI for Cl,should achieve much high accuracy due to the employment of the large correlation-consistent basis sets.     

房间出口位置及内部布局对疏散效率的影响研究

利用先前建立的元胞自动机人员疏散模型,考虑教室类房间内过道区域的影响因素,调整行人转移概率的计算规则,分析了教室不同出口位置、教室内不同布局情况下的疏散效率.结果表明,正对教室过道的出口对疏散是很有利的,教室正面边缘开口和侧面开口相比,宜在侧面开口,以减少行人运动过程中方向的变化,而教室正面中央开口虽然疏散效率最高,但这样的开口不现实;另外,当教室侧面开口时,紧靠出口墙壁侧的过道是必要的,当教室总容量不变时,应优先考虑过道分布的设计,过道的数目和单个过道宽度相比,过道数目对疏散效率的影响更显著,过道数量较多时,疏散效率较高.本文有望为教室内部布局和出口设置,以及影剧院、体育馆看台等类似建筑内座椅和过道的分布设计提供建议.     

BeO高压相变和声子谱的第一性原理计算

采用第一性原理方法计算了BeO在零温时的高压相变和三种结构在零温零压时的声子谱.相变的计算表明,在122GPa左右的压力下BeO会发生从纤锌矿(B4)结构到氯化钠(B1)结构的相变,而闪锌矿(B3)结构在零温零压下是一种可能的亚稳态结构.采用冷声子方法计算了这三种结构的BeO在零温零压下的声子谱.计算结果表明:B1结构在零温零压下是一种不稳定的结构;尽管B4结构和B3结构具有明显的相似性,仍然可以通过声子谱来很好的区分.最后根据准简谐近似理论计算得到了BeO的高温高压相图.     

Analysis method of the effect of fabrication errors on a planar waveguide demultiplexer

The impact of fabrication errors on a planar waveguide demultiplexer is analyzed based on an analytical method. The explicit expression of the transfer function taking into account phase and amplitude errors is presented in order to analyze the loss and crosstalk of the demultiplexer caused by fabrication errors. A basic requirement for the demultiplexer with a certain crosstalk criterion can be easily obtained. Using an etched diffraction grating demultiplexer as an example, it is shown that the analytical results have a good agreement with results from a numerical method.