一种特殊条件下的扩散方程的数值解法及物理分析

利用有限差分方法中的预估校正格式求解裂变产物在燃料芯块中的扩散方程,并进行了灵活的边界条件处理,取得了令人满意的计算精度,为有效开展对反应堆燃料元件破损探测信号的定量分析提供了条件.对数值计算过程进行了一定的物理分析,从物理意义上解释了数值计算过程中一些特殊处理的合理性.     

Generalizations of ?wierczkowski’s lemma and the arity gap of finite functions

?wierczkowski’s lemma-as it is usually formulated-asserts that if f:Aⁿ→A is an operation on a finite set A, n≥4, and every operation obtained from f by identifying a pair of variables is a projection, then f is a semiprojection. We generalize this lemma in various ways. First, it is extended to B-valued functions on A instead of operations on A and to essentially at most unary functions instead of projections. Then we characterize the arity gap of functions of small arities in terms of quasi-arity, which in turn provides a further generalization of ?wierczkowski’s lemma. Moreover, we explicitly classify all pseudo-Boolean functions according to their arity gap. Finally, we present a general characterization of the arity gaps of B-valued functions on arbitrary finite sets A.     

光子晶体偏振分光镜的优化设计

提出了一种二维光子晶体偏振分光镜的设计方法,介绍了光栅基板上用Ge/BaF₂ 多层膜实现二维光子晶体偏振分光镜的优化设计.结果表明，TE模式的光子禁带宽度为0083(2πc/a, a是光栅的周期),设计的偏振波长从172μm到24μm，相对带宽为331％.此光子晶体偏振器件制作简单,具有实用性. 关键词： 偏振分光镜 光子晶体 光子禁带     

Nonlinear dynamical stability of gap solitons in Bose-Einstein condensate loaded in a deformed honeycomb optical lattice

We investigate the existence and dynamical stability of multipole gap solitons in Bose-Einstein condensate loaded in a deformed honeycomb optical lattice. Honeycomb lattices possess a unique band structure, the first and second bands intersect at a set of so-called Dirac points. Deformation can result in the merging and disappearance of the Dirac points, and support the gap solitons. We find that the two-dimensional honeycomb optical lattices admit multipole gap solitons. These multipoles can have their bright solitary structures being in-phase or out-of-phase. We also investigate the linear stabilities and nonlinear stabilities of these gap solitons. These results have applications of the localized structures in nonlinear optics, and may helpful for exploiting topological properties of a deformed lattice.     

Liquid densities of THF and excess volumes for the mixture with water in a wide temperature and pressure range

In this paper densities for THF (tetrahydrofuran) and THF + water mixtures measured with the help of the Anton Paar DMA HPM vibrating tube densimeter are reported. The pure component densities of tetrahydrofuran measured in the temperature range from 278 to 437 K and pressures up to 130 MPa were correlated with the TRIDEN-System. Additionally densities of the binary mixture tetrahydrofuran + water were measured for 6 different concentrations in a temperature range from 288 to 338 K and up to 130 MPa. Excess volumes (vE)$(v^E)$ of the mixture were determined using the own correlation of the tetrahydrofuran densities and the equation of state (EoS) for water by Wagner and Pruß. Redlich–Kister polynomials were used to fit the vE-data$v^E\text{-data}$. Additionally in this work it was checked if the vibrating tube densimeter allows the determination of the miscibility gap for the system THF–water as a function of temperature and pressure.     

多类型复发间隔时间下广义半参数风险模型

本文在多类型复发间隔时间数据下,研究了一类广义半参数风险回归模型的参数估计问题,给出了该模型中未知参数和非参数函数的一种估计方法,并证明了估计量的相合性和渐近正态性.最后利用数值模拟来评估估计量在有限样本下的表现.     

射频磁控溅射法制备N掺杂β-Ga2O3薄膜的光学特性

在不同氨分压比(0～30％)下,用射频磁控溅射法在玻璃和硅衬底上制备了N掺杂β-Ga2O3薄膜.研究了氨分压比和退火对薄膜光学和结构特性的影响.N掺杂β-Ga2O3薄膜的微结构、光学透过率、光学吸收和光学带隙随着氨分压比的增加发生了显著变化.观察到了绿光、蓝光和紫外发光带,并对每个发光带进行了讨论.     

超二代微光像增强器Na2KSb(Cs)多碱光电阴极荧光谱研究

利用785 nm波长激光作为激发源,测量了超二代微光像增强器Na2 KSb (Cs)多碱光电阴极的荧光谱.试验中发现该荧光谱不是一条光滑的高斯型曲线,而是一条在高斯型荧光谱上叠加了一定频率间隔小锯齿峰的曲线.经实验验证和理论分析证明该荧光谱上的小锯齿峰是一种干涉条纹,与超二代微光像增强器的结构有关.干涉条纹之间的间距与...     

Geometrically distributed aperiodic circular photonic crystals with broad and isotropic photonic band gaps

In this paper, a new type of circular photonic crystal (CPC) with a geometrical distribution of concentric layers is presented. A broad and isotropic photonic band gap is achieved using this geometrically distributed CPC (GCPC). Also, the influence of the number of concentric layers to the overall band gap of GCPC is studied. It is demonstrated that the band gap broadens with a red shift when the number of concentric layers is increased. The reason for the red shift of the band gap is further investigated.