横向放大率法确定复合光学系统的基点

介绍了应用测量横向放大率确定两薄透镜组成的复合光学系统基点的方法。由于采用线阵光电耦合器件（CCD）测量物经光学系统成像的横向放大率，提高了测量精度。     

The studies of high-temperature and short-time annealing,phase transition process,and magnetic property for LaFe11.7Si1.3 compound

The high-temperature phase transition is analyzed according to the DSC of as-cast LaFe_11.7 Si_1.3 compound and the X-ray patterns of LaFe_11.7Si_1.3 compounds prepared by high-temperature and short-time annealing. Large amount of 1:13 phase begins to appear in LaFe_11.7Si_1.3 compound annealed near the melting point of LaFeSi phase (about 1422?K). When the annealing temperature is close to the temperature of peritectic reaction (about 1497?K), the speed of 1:13 phase formation is the fastest. The phase relation and microstructure of the LaFe_11.7Si_1.3 compounds annealed at 1523?K (5?h), 1373?K (2?h)?+?1523?K (5?h), and 1523?K (7?h) +1373?K (2?h) show that longer time annealing near peritectic reaction is helpful to decrease the impurity phases. For studying the influence of different high-temperature and short-time annealing on magnetic property, the Curie temperature, thermal, and magnetic hystereses, and the magnetocaloric effect of LaFe_11.7Si_1.3 compound annealed at three different temperatures are also investigated. Three compounds all keep the first order of magnetic transition behavior. The maximal magnetic entropy change ΔS_M (T, H) of the samples is 12.9, 16.04, and 23.8?J?kg^?1?K^?1 under a magnetic field of 0–2?T, respectively.     

重离子熔合反应与双核模型

简单介绍了兰州-北京-吉森合作组对合成超重核的重离子反应进行的初步研究。研究的重点是熔合阶段的反应机制。在原有双核模型的基础上做了一些改进,把耗散相对运动过程与核子转移过程耦合起来,从更微观的角度来描写双核系统向全熔合复合核的演化。在双核过程中的每一步求解主方程,不对驱动势做谐振子近似。同时,还探讨了原子核形变与相对取向对驱动势的影响,存活几率与复合核蒸发中子的奇偶效应,以及入射道中原子核非弹性激发对俘获截面的影响等。In recent years, the Lanzou-Beijing-Giessen collaboration has studied the heavy ion reactions which are lead to the formation of super-heavy nuclei. The study emphases the mechanism of the fusion stage of the reactions. Based on the so called Di-nuclear System Model, some improvements have been made. The main points are the coupling of the dissipation of relative motion energy, angular momentum with nucleon transfer, and solving the Master equation in every step of the nucleon transfer with exact driving potentials, in order to describe the evolution of the system more microscopically. At the same time, we also discussed the effects of nuclear deformation and their relative orientation on the driving potentials, and studied the survive probability of the compound nuclei and its old-even effects, as well as the influence of inelastic excitations of nuclei in entrance channels to the capture cross sections.     

大学物理实验的简化与深化

以复摆实验、地磁实验和衍射光栅实验为例,说明在大学物理实验中,通过提供简单的实验器材,就可以将实验内容延伸扩展,将原来内容单一的实验扩展为多层次、多目的的实验项目,实现大学物理实验的简化与深化.     

Sn Mössbauer spectroscopy of Gd0.8L0.2Mn6Sn6 and Tb0.8L0.2Mn6Sn6 compounds (L=Sc,Y, Lu)

The HfFe₆Ge₆-type compounds Gd_0.8L_0.2Mn₆Sn₆ and Tb_0.8L_0.2Mn₆Sn₆ (L = Sc, Y, Lu) have been studied by ¹¹⁹Sn Mössbauer spectroscopy. The values of the apparent quadrupolar splitting clearly evidence the easy plane magnetization of the gadolinium compounds and the easy axis one in the terbium compounds. The three tin sites behave differently with the nature and size of the substituting L element. For a given series, the hyperfine field of the Sn_2d site is almost unchanged whatever the size of the L element. The hyperfine field of the Sn_2e site strongly varies with the L size in relation with atomic displacements. The hyperfine field of the Sn_2c site exhibits a more complicated behavior. The field difference in the easy plane and easy axis compounds confirms the angle-dependent anisotropic contribution of the Mn moment to the hyperfine field. The analysis of the results also suggests the play of angle-dependent contributions arising from the rare earth moment.     

Thermodynamic and physical properties of FeAl and Fe3Al: an atomistic study by EAM simulation

With this work we present a newly developed potential for the Fe–Al system, which is based on the analytical embedded atom method (EAM) with long range atomic interactions. The potential yields for the two most relevant phases B2-FeAl and D0₃-Fe₃Al lattice constants, elastic constants, as well as bulk and point defect formation enthalpies, which are in good agreement with experimental and other theoretical data. In addition, the phonon dispersions for B2-FeAl and D0₃-Fe₃Al show a good agreement with available experiments. The calculated lattice constants and formation enthalpy for disordered Fe–Al alloys are in good agreement with experimental data or other theoretical calculations. This indicates that the present EAM potentials of Fe–Al system is suitable for atomistic simulations of structural and kinetic properties for the Fe–Al system.     

Ni13Pr3B2电子结构和磁性能第一性原理研

考虑电子自旋极化作用,本研究基于第一性原理的全电子投影缀加平面波赝势法理论,采用局域自旋密度近似LSDA,对Ni13Pr3B2金属间化合物进行结构优化,计算体系晶格常数,电子结构和磁性能。结果表明,Ni13 Pr 3B2为带隙很小的金属导体。LSDA近似下体系原子间存在复杂作用类型,Pr原子与近邻Ni、B原子以离子键作用为主,Ni原子与近邻Ni原子间表现共价作用情形。体系存在Pr -Ni铁磁耦合,总磁矩约2.80212μB,主要由Pr原子磁矩提供,自旋极化引起体系Pr-4f、Ni-3p、Pr-5p电子自旋劈裂为体系表现磁性的根本原因。     

Tb2Fe15.5Cr1.5化合物的本征磁致伸缩

通过x射线衍射及磁测量手段研究了Tb2 Fe1 5 5Cr1 5化合物的热膨胀性质及本征磁致伸缩性质 .研究结果表明Tb2 Fe1 5 5Cr1 5化合物在 2 93— 6 72K的温度范围内具有六角相的Th2 Ni1 7型结构 .在 4 32— 5 2 2K的温度范围内具有负热膨胀性质 ,其平均热膨胀系数 α =- 1 5 7× 10 - 5 K .对本征磁致伸缩的研究结果表明Tb2 Fe1 5 5Cr1 5化合物中存在着较强的各向异性的本征磁致伸缩 ,2 93K时其本征体磁致伸缩约为 8. 4× 10 - 3,晶格畸变主要发生在c轴方向上 .磁测量研究结果表明Tb2 Fe1 5 5Cr1 5化合物的居里温度约为 4 94K ,比其母合金Tb2 Fe1 7高约 80K .     

斜孔气膜冷却数值模拟分析

本文通过数值模拟分析圆柱孔和扩散孔的单斜孔气膜冷却特性,考察复合角、孔型和吹风比对流场和气膜冷却效果的影响。结果表明,复合角的引入使气膜侧向分布更宽,但冷却效果沿主流方向衰减更快。适中吹风比得到的气膜能更有效的保护壁面。在相同吹风比和复合角条件下,扩散孔的气膜冷却效率比圆柱孔更好,且冷却更为均匀持久。     

纳米ZnO的表面化学修饰及其分析表征

采用水溶性羟丙基甲基纤维素HPMC对无机纳米ZnO粒子进行物理吸附处理 ,获得了核为无机纳米ZnO ,外壳为水溶性高分子HPMC的粒子。然后在其上进行了甲基丙烯酸甲酯的接枝聚合。采用红外光谱、差热分析的方法对复合粒子进行了表征 ,并采用透射电镜观察了粒子的形貌。红外光谱表明在纳米ZnO的表面吸附了HPMC并接枝了PMMA ,差热分析表明HPMC ,HPMC g PMMA和ZnO/HPMC g PMMA的热稳定性逐渐提高 ,透射电镜观察表明 ,在纳米ZnO的表面粘附了一层聚合物 ,成功地实现了纳米粒子的表面修饰。