Quantum Statistical Properties in Two—Species Bose—Einstein Condensates

We have studied quantum statistical properties in a zero-temperature two-species Bose-Einstein condensate system in the presence of the nonlinear self-interaction of each species,the interspecies nonlinear interaction,and the Jisephson-like tunneling interaction.It is found that the two condensates may periodically exhibit sub-Poissonian distribution.It is revealed that the correlation between the two condensates can be nonclassical,which means that there exists a violation of Cauchy-Schwartz inequality.The nonclassical effect about the correlation between the two condensates can be realized experimentally by properly preparing the total number of atoms in the two condensates.     

Self—Trapping State and Atomic Tunnelling Current of an Atomic Bose—Einstein Condensate Interacting with a Laser Field in a Double—Well Potential

We present a theoretical treatment of dynamics of an atomic Bose-Einstein condensation interacting with a single-mode quantized travelling-wave laser field in a double-well potential.When the atom-field system is initially in a coherent state,expressions for the energy exchange between atoms and photons are derived.It is revealed that atoms in the two wells can be in a self-trapping state when the tunnelling frequency satisfies two specific conditions,in which the resonant and far off-resonant cases are included.It is found that there is an alternating current with two different sinusoidal oscillations between the two wells,but no dc characteristic of the atomic tunnelling current occurs.It should be emphasized that when without the laser field,both the population difference and the atomic tunnelling current are only a single oscillation.But they will respectively become a superposition of two oscillations with different oscillatory frequencies in the presence of the laser field.For the two oscillations of the population difference,one always has an increment in the oscillatory frequency,the other can have an increment or a decrease under different cases.These conclusions are also suitable to those of the atomic tunnelling current.As a possible application,by measurement of the atomic tunnelling current between the two wells,the number of Bose-condensed atoms can be evaluated.By poperly selecting the laser field,the expected atomic tunnelling current can be obtained too.     

An effective potential method for the calculation of hydrogen molecule ion energy in a strong magnetic field

Using the adiabatic approximation and adiabatic variational approximation with an effective potential, the total energies and the equilibrium internuclear separations of H₂⁺ ion in states σ_g, π_u, δ_g, φ_u, γ_g, η_u in strong magnetic fields have been calculated. Our results reproduced those obtained by Vincke and Baye (Vincke M and Baye D 1985 J. Phys. B: At. Mol. Phys. 18 167), which are considered the most reliable. We found a basic function with better convergence than the Landau functions.     

CO在Pt低指数面上吸附行为的理论研究

用密度泛函理论(DFT)中的广义梯度近似(GGA)方法对CO-Pt低指数面吸附体系进行了结构优化, 并对吸附体系的吸附热、C—O键和C—Pt键的键长、布居数分析、电子态密度进行了研究. 计算结果表明, 在0.25 ML(monolayer)的覆盖率下, CO最容易在Pt(100)晶面的桥位、Pt(110)晶面的短桥位、Pt(111)晶面的hcp三重位吸附, 吸附热分别达到了2.11、2.37、1.96 eV; CO在吸附成键过程中伴有电子在CO分子和Pt之间的转移. 吸附后, C—O键被削弱, 键长变长, 金属内部的作用亦被削弱, 其表层Pt 原子的布居数明显降低; 态密度分析表明, CO在吸附过程中, 其4σ、1π、5σ、2π轨道均参与成键.     

Lie Symmetrical Non-Noether Conserved Quantity of Mechanical System in Phase Space

In this paper, we study the Lie symmetrical non-Noether conserved quantity of the differential equations of motion of mechanical system in phase space under the general infinitesimal transformations of groups. Firstly. we give the determining equations of the Lie symmetry of the system. Secondly, the non-Noether conserved quantity of the Lie symmetry is derived. Finally, an example is given to illustrate the application of the result.     

孔眼流入对水平井中流动影响的实验研究

设计并建立了水平井筒变质量流动模拟实验装置。对具有射孔完井的水平井筒变质量流动进行了实验研究,利用先进的数据采集系统获取了大量的实验数据。对水平井井筒单孔眼段流动阻力损失分析可知,流动阻力由三部分组成：管壁摩擦阻力、加速损失和混合损失。对实验数据进行处理得出了混合损失和主流流速与孔眼流速之间的关系。对于一定的主流流速,混合损失随孔眼流速的增大而增大,同时,对于一定的孔眼流速,混合损失随主流流速的增大而增大,此时孔眼的流入对水平井筒中的流动造成的影响比较显著。孔眼的流入增加了井筒中流动的复杂性。对实验数据进行的回归结果表明,在本实验条件和范围内,主流流速和孔眼流速是造成混合损失的主要因素。     

Hydrothermal synthesis and structural determination of a three-dimensional microporous iron(III)phosphate: [H3N(CH2)4NH3]3[Fe8(HPO4)12(PO4)2(H2O)6]

A new microporous iron (III) phosphate, [H₃N(CH₂)₄NH₃]₃[Fe₈(HPO₄)₁₂(PO₄)₂(H₂O)₆], has been prepared using low temperature hydrothermal methods and characterized by single-crystal X-ray diffraction, EDAX, infrared spectroscopy, thermogravimetric analysis and bond valence sums. The title compound crystallizes as light pink hexagonal-shaped tabs in the centrosymmetric hexagonal space group 3¯ (No.147) with a = b = 13.495(2) Å, c = 9.396(2) Å, V = 1481.9(4) ų and Z = 4 with R/R_w = 0.044/0.048. The compound exhibits a complicated three-dimensional microporous structure with quaternary ammonium ions acting as a template for the framework. It is similar to previously reported [HN(CH₂CH₂)₃NH]₃[Fe₈(HPO₄)₁₂(PO₄)₂(H₂O)₆].     

Noether's theory of generalized linear nonholonomic mechanical systems

By introducing the quasi-symmetry of the infinitesimal transformation of the transformation group G_r, the Noether's theorem and the Noether's inverse theorem for generalized linear nonholonomic mechanical systems are obtained in a generalized compound derivative space. An example is given to illustrate the application of the result.     

不同型面微孔对激光加工多孔端面机械密封性能的影响

考虑密封端面液膜中的空化现象,建立了激光加工多孔端面机械密封(LST-MS)的理论分析模型,应用有限元方法研究了矩形面、椭圆面、球缺面和抛物面等4种不同型面微孔LST-MS的密封特性参数,包括端面开启力、液膜刚度和摩擦扭矩等受微孔几何结构参数的影响规律,给出了上述LST-MS在最大液膜刚度条件下微孔的最优面积密度和最优深径比.结果表明,矩形型面微孔LST-MS拥有最佳的综合性能,研究结果具有较强的理论与工程应用价值.