Spectroscopic Studies on Charge Transfer from Ce~(3 ) to Yb~(3 ) in KMgF_3∶Ce,Yb Nanocrystals

Nanocrystals of KMgF3 single-doped and codoped with Ce3 or/and Yb3 were synthesized separately by the microemulsion method.The X-ray diffraction(XRD)patterns were indexed to show that the KMgF3 crystal system was unchanged.The fluorescent spectra of KMgF3∶Ce,Yb polycrystal powders were studied and compared with those of the Ce,Yb doped KMgF3 crystals produced using the high-temperature solid phase method.The diffuse reflection spectra and infrared emission of KMgF3∶Ce,Yb were investigated.From the results,the authors could confirm that there were charge transfer processes from Ce3 to Yb3 in both KMgF3∶Ce,Yb nanocrystals and polycrystal powders.     

原子和离子的f^k与g^k的计算方法

本文给出了原子和离子能量表达式中的库仑积分与交换积系数ｆ＾ｋ，ｇ＾ｋ的计算方法，同时给出了计算中所涉及的Ｒａｃａｈ系数，Ｕ＾（＾Ｋ＾），Ｖ＾（＾Ｋ＾）和Ｃ＾（＾Ｋ＾）矩阵等光谱参量的计算方法，用ＦＯＲＴＲＡＮⅣ语言编写了关于ｆ＾ｋ和ｇ＾ｋ的计算机程序，只要输入与光谱项有关的量子数，即可迅速得到相应的ｋ＾ｆ，ｇ＾ｋ值，避免了烦琐的人工推算。     

平台石墨炉原子吸收法测定高温镍基合金中砷

研究了基体改进剂，灰化，原子化温度和共存元素的干扰。采用钯作基体改进剂和匹配基体镍后，提高了灵敏度，增强了抗干扰能力。在波长１９７．２ｎｍ处，用平台石墨炉原子吸收法直接测定了高温镍基合金中砷。方法特征是为８８ｐｇ，检出限为０．２７μｇ．ｇ＾－１，相对标准偏差为３．１％－５．１％，回嵋率为８５％－１００％。     

2～4μm波长的InAsPSb异质结激光管材料的液相外延

采用液相外延方法,生长出外延层与衬底之间的失配度△α/α≤1.6×10-3界面平直、组分恒定的InAsPSb/InAs外延晶体.单异质结外延层,得到了3.09μm波长的激光输出,双异质结外延片也得到了较好的伏-安特性曲线.     

Sturm-Liouville边值问题解的非存在性、存在性和多重性结果

本文研究下述Sturm-Liouville边值问题利用Schauder不动点定理、上下解方法和Leray-Schauder映射度理论,获得了解的非存在性、存在性和多重性结果.其中一些是全新的结果,另一些则扩展、改进和完善了由Erbe,Wang,Hai,Lee和Lin所获得的结果.     

Generalized Derivations with Skew Nilpotent Values on Lie Ideals

This article gives characterizations of generalized derivations with skew nilpotent values on noncommutative Lie ideals of a prime ring. The results simultaneously generalize the ones of Herstein, Lee and Carini et al.     

Numerical study of vortex reconnection for two anti-parallel vortex tubes

By direct numerical simulation of the Navier-Stokes equations we investigate the reconnection of two antiparallel vortex tubes. A new type of perturbation of the initial vorticity field is given which is different from that presented in Refs. [8] and [9]. The formation and the evolution of the “curved vortex belts”, their mutual action with the “bridges” are found. These are important phenomena not studied by others. The project supported by the LNM of Institute of Mechanics, Academia Sinica and The National Natural Science Foundation of China     

HOMOGENIZATION—BASED TOPOLOGY DESIGN FOR PURE TORSION OF COMPOSITE SHAFTS

In conjunction with the homogenization theory and the finite element method, the mathematical models for designing the corss-section of composite shafts by maximizing the torsion rigidity are developed in this paper. To obtain the extremal torsion rigidity, both the cross-section of the macro scale shaft and the representative microstructure of the composite material are optimized using the new models. The micro scale computational model addresses the problem of finding the periodic microstructures with extreme shear moduli. The optimal microstructure obtained with the new model and the homogenization method can be used to improve and optimize natural or artificial materials. In order to be more practical for engineering applications, cellular materials rather than ranked materials are used in the optimal process in the existence of optimal bounds for the elastic properties. Moreover, the macro scale model is proposed to optimize the cross-section of the torsional shaft based on the tailared composites. The validating optimal results show that the models are very effective in obtaining composites with extreme elastic properties, and the cross-section of the composite shaft with the extremal torsion rigidity. The project supported by the National Natural Science Foundation of China (10172078 and 10102018)     

纺织结构复合材料力学性能的实验研究

本文通过实验测定了三维编织结构复合材料侧边未切割、受切割和中央钻孔试件的拉伸性能，对比了受切割和未切割纤维对于试件侧边拉伸应变的影响，并且讨论了拉伸失效的机理和原因．发现受切割和钻孔试件的拉伸性能低于未加工试件的性能，受切割侧边的拉伸应变高于未切割侧边的拉伸应变，三维编织结构复合材料的拉伸失效主要由纤维断裂引起的．文中还对三维编织结构复合材料的孔边应力集中现象进行了研究，并进行了深入分析，得到一个重要结论，即四步法复合材料的孔边应力集中系数比传统层板复合材料和金属材料的低．从这个意义上说，三维编织结构复合材料适合于作为含孔结构的连接件．