DECOMPOSITION, REPRESENTATION AND EXTENSION OF THE HARMONIC FUNCTIONS

In this paper, by using the probabilistic method, we obtained a decomposition theorem for the harmonic functions, generalized and strengthened some theorems: Doob's theorem on the limit behaviors of the superharmonic functions, Bocher's theorem on the representation of the harmonic functions and the extension theorem of the harmonic functions etc.     

Critical rotation of an anharmonically trapped Bose--Einstein condensate

We consider rotational motion of an interacting atomic Bose-Einstein condensate (BEC) with both two- and three-body interactions in a quadratic-plus-quartic and harmonic-plus-Gaussian trap. By using the variational method, the influence of the three-body interaction and the anharmonicity of the trap on the lowest energy surface mode excitation and the spontaneous shape deformation (responsible for the vortex formation) in a rotating BEC is discussed in detail. It is found that the repulsive three-body interaction helps the formation of the vortex and reduces the lowest energy surface mode frequency and the critical rotational frequency of the system. Moreover, the critical rotational frequency for the vortex formation in the harmonic-plus-Gaussian potential is lower than that in the quadratic-plus-quartic potential.     

用实验方法探讨检流计偏转格数与电桥灵敏度的关系

由电桥灵敏度的定义可知,△n是对应于待测电阻的相对改变量,而引起检流计中的偏转量,所以电桥灵敏度越大,对电桥平衡的判断就越容易准确,测量结果也更准确.那么用实验方法测定电桥灵敏度时,△n取值是多少格合适?本文用实验方法探讨了检流计偏转格数与电桥灵敏度的关系.     

铁电纳米材料BaTiO_3的激光拉曼光谱分析

铁电纳米材料BaTiO_3具有尺寸均匀,形貌统一的单晶纳米立方体结构。以LRS-Ⅲ型激光拉曼/荧光光谱仪为测量仪器研究其在固体纳米材料BaTiO_3分析中的应用。用碱热法制作得到4种无掺杂铁电纳米材料BaTiO_3,分别标记为纯1、纯2、纯3、纯4,将四种固体纳米材料作为标样待测;另取两个不同浓度Eu(铕)元素掺杂的材料分别标记为掺杂1、掺杂2待测。本实验中,不仅对比分析了不同烧结温度和时间下的固体纳米材料BaTiO_3激光拉曼光谱,并做出了相应的解释说明。与此同时,对掺杂BaTiO_3的也做了拉曼光谱对比分析,研究掺杂对固体材料拉曼谱线的影响。研究结果表明,含有相同成分的固体材料其拉曼谱线相似,且不同掺杂引起拉曼谱线的变化不同。最后用相关系数对掺杂材料和无掺杂材料做了进一步分析。从总体来看类内相关系数较高而类间相关系数较低,但即便掺杂的量比较少,对相关系数也有明显的影响。结合相关系数可以明确地判断出两种物质是否同类,如果已知某一种没有掺杂,那么,就可以很容易地判断出另一种材料中是否有掺杂。     

Effect of Tidal Torques on Rotational Mixing in Close Binaries

The effect of tidal torques on rotational mixing in close binaries is investigated. It is found that spin angular momentum can attain a high value due to a strong tidal torque. Nitrogen and helium enrichment occurs early in the binary system that is triggered by tides. The stellar radius can reach a high value in the single star model with high initial velocities at the early stage of the evolution, but efficient rotational mixing can inhibit stellar expanding at the subsequent evolution. Central compactness is increased by the centrifugal force at the early stage of evolution but is reduced by rotational mixing induced by strong tides. The binary models with weak tides have high values of central temperature and stellar radius. Rotational mixing in single stars can slow down the shrinkage of convective cores, while convective cores can be expanded by strong tides in the binary system.Efficient rotational mixing induced by tides can cause the star to evolve towards high temperature and luminosity.     

Direct Observation of High-Temperature Superconductivity in One-Unit-Cell FeSe Films

We prepared one-unit-ceil （1-UC） thick FeSe films on insulating SrTiOa substrates with non-superconducting FeTe protection layers by molecular beam epitaxy for ex situ studies. By direct transport and magnetic measurements, we provide definitive evidence for high temperature superconductivity in the 1-UC FeSe films with an onset Tc above 40 K and an extremely large critical current density fie Jc-1.7× 106 A/cm2 at 2K, which are much higher than Tc-8K and Jc-104 A/cm^2 for bulk FeSe, respectively. Our work may pave the way to enhancing and tailoring superconductivity by interface engineering.     

用转轮演示载流导线在磁场中的受力

介绍了用转轮方式演示载流导线在磁场中受力的原理和演示方法。     

计算机控制在物理演示实验教学中的应用示例

在物理演示实验教学中充分发挥计算机控制的作用,可实时地记录实验曲线,分析实验数据,并与理论结果相比较.通过计算机控制的演示与实习实验能激发学生学习物理的兴趣,提高教学质量.     

衍射光栅光谱级数与实验误差的关系研究

从理论上证明了光栅衍射的光谱级数与实验绝对误差的关系,得到二级衍射谱线的精度高于一级衍射谱线的精度,从而能降低实验误差。依据实验数据,计算得到衍射光谱级数不同时的波长,实验结果与理论结论是相吻合的。     

基于地方特色开发的化工过程模拟实验——以变压精馏为例

基于六盘水地区海拔高、气压低的特点,开设了具有地方特色的变压精馏过程模拟实验,低压塔设定为六盘水地区大气压值。以变压精馏分离乙酸甲酯-甲醇共沸物为例,通过相图确定精馏序列及工艺流程,讨论了进料位置、回流比和塔板数等变量对年度总费用TAC的影响,对于学生掌握化工技术和经济分析具有良好的教学效果。同时,对于培养人才的工程实践能力和服务地方产业提供了有效的保障。