Inequalities for dual quermassintegrals of mixed intersection bodies

In this paper, we first introduce a new concept ofdual quermassintegral sum function of two star bodies and establish Minkowski’s type inequality for dual quermassintegral sum of mixed intersection bodies, which is a general form of the Minkowski inequality for mixed intersection bodies. Then, we give the Aleksandrov-Fenchel inequality and the Brunn-Minkowski inequality for mixed intersection bodies and some related results. Our results present, for intersection bodies, all dual inequalities for Lutwak’s mixed prosection bodies inequalities.     

TiO2纳米管阵列的制备、改性及其应用研究进展

新型纳米材料TiO₂纳米管阵列具有独特的、高度有序的阵列结构和良好的力学性能、化学稳定性以及抗腐蚀性能。该材料以纯金属钛为基体，在含有少量氟离子的电解质溶液中通过电化学阳极氧化法制得。本文综述了近年来TiO₂纳米管阵列在不同电解液体系中的制备工艺、形成机理、修饰改性及其在光催化降解污染物、太阳能电池、气敏传感材料、光解水制氢等领域应用的最新研究成果，并指出目前存在的问题，对今后的研究提出了展望。     

Growth of Strain Free GaN Layers on （0001） Oriented Sapphire by Using Quasi-Porous GaN Template

We report the reduced-strain gallium-nitride （GaN） epitaxial growth on （0001） oriented sapphire by using quasiporous GaN template. A GaN film in thickness of about 1 μm was initially grown on a （0001） sapphire substrate by molecular beam epitaxy. Then it was dealt by putting into 45% NaOH solution at 100℃ for lOmin. By this process a quasi-porous GaN film was formed. An epitaxial GaN layer was grown on the porous GaN layer at 1050℃ in the hydride vapour phase epitaxy reactor. The epitaxial layer grown on the porous GaN is found to have no cracks on the surface. That is much improved from many cracks on the surface of the GaN epitaxial layer grown on the sapphire as the same as on GaN buffer directly.     

Eu原子4f~76snlRydberg态的研究

利用三步双色共振激发技术和三步三色孤立实激发技术,系统地研究了铕原子在42250—44510 cm~(-1)能域内的光谱特性,提供了该能域内56个束缚高激发态的光谱信息.为了能确定这些态的光谱归属,进行了两方面的探索:第一,观察能否利用孤立实激发技术,把处于这些态上的铕原子进一步共振激发到自电离态,从而推断这些态属于单电子激发的束缚Rydberg态还是属于双电子激发的价态,并对Rydberg态的电子组态进行了光谱确认;第二,通过计算这些态相对于各个电离阈的量子亏损并观察它们分别收敛于哪个电离阈,以便获取其主量子数的信息.最后,设计并采用了三种不同的激发路径,分别将原子布居到同一高激发能域并探测它们在该能域的光电离光谱.通过比较这些光谱的异同并结合上述激发路径所对应的跃迁选择定则,便可惟一地确定这些高激发态的总角动量.研究发现:所探测到的高激发束缚态只有三个属于单电子激发的束缚Rydberg态,其余都是价态.本文确定了这三个Rydberg态的电子组态和原子状态.     

Strong nonlinearity analysis for gear-bearing system under nonlinear suspension—bifurcation and chaos

This study performs a systematic analysis of the dynamic behavior of a gear-bearing system with nonlinear suspension, nonlinear oil-film force, and nonlinear gear mesh force. The dynamic orbits of the system are observed using bifurcation diagrams plotted with both the dimensionless unbalance coefficient and the dimensionless rotational speed ratio as control parameters. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, Lyapunov exponents, and fractal dimensions of the gear-bearing system. The numerical results reveal that the system exhibits a diverse range of periodic, sub-harmonic, and chaotic behaviors. The results presented in this study provide an understanding of the operating conditions under which undesirable dynamic motion takes place in a gear-bearing system and therefore serves as a useful source of reference for engineers in designing and controlling such systems.     

Eu原子4f~76p_(3/2)ns自电离衰变分支比和弹射电子角分布

首先运用孤立实激发技术将Eu原子从基态4f~76s~(28)S_(7/2)经中间态4f~76s6p共振激发到4f~76sns Rydberg态,然后再将其进一步激发至4f~76p_(3/2)ns(n=7,8)自电离态.其次,采用速度影像技术对Eu原子自电离弹射出的电子进行探测,以便来研究自电离衰变分支比和弹射电子角分布.在研究自电离衰变分支比时,重点讨论了粒子数反转的可能性,并依据此现象可为实现自电离激光器提供有价值的信息.另外,还探讨了各向异性参数对弹射电子角分布的影响;以及在Eu原子不同自电离几率位置处,讨论了弹射电子角分布形状的变化情况.     

低温分子束外延生长的GaMnAs反射光谱的低能振荡现象

通过傅里叶变换红外光谱和光调制反射光谱技术测量了不同Mn含量的低温分子束外延生长在GaAs衬底上的GaMnAs样品的反射光谱.在低于Ga(Mn)As带边的红外反射光谱和光调制反射光谱上观测到低能振荡现象.通过分析振荡产生的原因并使用双层界面反射模型拟合了红外反射光谱的低能振荡过程,拟合结果与实验相符.研究表明,反射光谱的低能振荡是由于GaMnAs中空穴浓度的变化导致GaMnAs中的折射率发生变化,GaMnAs与衬底GaAs之间的折射率差导致了不同Mn含量的GaMnAs材料的反射谱的低能振荡现象.测量了不同 关键词： GaMnAs 反射光谱 空穴浓度 折射率     

衬底对Cu(In,Ga)Se2薄膜织构的影响

分别在苏打石灰玻璃、Mo箔、无择优取向的Mo薄膜以及(110)择优取向的Mo薄膜四种不同衬底上,采用共蒸发工艺沉积约2μm厚的Cu(In,Ga)Se2薄膜,用X射线衍射仪测量薄膜的织构,研究衬底对Cu(In,Ga)Se2薄膜织构的影响.在以上四种衬底上沉积的Cu(In,Ga)Se2薄膜的(112)衍射峰强度依次逐渐减弱,(220/204)衍射峰从无到有且强度逐渐增强.在苏打石灰玻璃和Mo箔衬底上的Cu(In,Ga)Se2薄膜具有明显的(112)择优生长,而在(110)取向的Mo薄膜衬底上,Cu(In,Ga)Se2薄膜的织构为(220/204)取向.研究结果表明,只有(110)择优取向的Mo薄膜衬底对Cu(In,Ga)Se2薄膜(220/204)织构的形成有重要影响.