双激光脉冲打靶形成Gd等离子体的极紫外光谱辐射

高端芯片制造所需要的极紫外光刻技术位于我国当前面临35项"卡脖子"关键核心技术之首.高转换效率的极紫外光源是极紫外光刻系统的重要组成部分.本文通过采用双激光脉冲打靶技术实现较强的6.7 nm极紫外光输出.首先,理论计算Gd¹⁸⁺—Gd²⁷⁺离子最外层4d壳层的4p-4d和4d-4f能级之间跃迁、以及Gd¹⁴⁺—Gd¹⁷⁺离子最外层4f壳层的4d-4f能级之间跃迁对波长为6.7 nm附近极紫外光的贡献.其后开展实验研究,结果表明,随着双脉冲之间延时的逐渐增加,波长为6.7 nm附近的极紫外光辐射强度呈现先减弱、后增加、之后再减弱的变化趋势,在双脉冲延时为100 ns处产生的极紫外光辐射最强.并且,在延时为100 ns处产生的光谱效率最高,相比于单脉冲激光产生的光谱效率提升了33%.此外,发现双激光脉冲打靶技术可以有效地减弱等离子体的自吸收效应,获得的6.7 nm附近极紫外光谱宽度均小于单激光脉冲打靶的情形,且在脉冲延时为30 ns时刻所产生的光谱宽度最窄,约为单独主脉冲产生极紫外光谱宽度的1/3.同时...     

局部分数阶拉普拉斯算子的狄利克雷问题弱解的细正则性

In this paper, we study the Holder regularity of weak solutions to the Dirichlet problem associated with the regional fractional Laplacian (-△)^αΩ on a bounded open set Ω ■R(N ≥ 2) with C^(1,1) boundary ■Ω. We prove that when f ∈ L^p(Ω), and g ∈ C(Ω), the following problem (-△)^αΩu = f in Ω, u = g on ■Ω, admits a unique weak solution u ∈ W^(α,2)(Ω) ∩ C(Ω),where p >N/2-2α and 1/2< α < 1. To solve this problem, we consider it into two special cases, i.e.,g ≡ 0 on ■Ω and f ≡ 0 in Ω. Finally, taking into account the preceding two cases, the general conclusion is drawn.     

Diffusion Model of a Non-Integer Order PIγ Controller with TCP/UDP Streams

In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller PIγ and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature.     

Negative thermal expansion in NbF_3 and NbOF_2:A comparative theoretical study

Thermal expansion control is always an obstructive factor and challenging in high precision engineering field. Here,the negative thermal expansion of Nb F_3 and Nb OF_2 was predicted by first-principles calculation with density functional theory and the quasi-harmonic approximation(QHA). We studied the total charge density, thermal vibration, and lattice dynamic to investigate the thermal expansion mechanism. We found that the presence of O induced the relatively strong covalent bond in Nb OF_2, thus weakening the transverse vibration of F and O in Nb OF_2, compared with the case of Nb F_3.In this study, we proposed a way to tailor negative thermal expansion of metal fluorides by introducing the oxygen atoms.The present work not only predicts two NTE compounds, but also provides an insight on thermal expansion control by designing chemical bond type.     

Additive Hermitian idempotent preservers between operator algebras

Let L be an additive map between (real or complex) matrix algebras sending $n\times n$ Hermitian idempotent matrices to $m\times m$ Hermitian idempotent matrices. We show that there are nonnegative integers $p,q$ with $n(p+q)=r\le m$ and an $m\times m$ unitary matrix U such that$L(A)=U[(I_p?A)\oplus (I_q?A^t)\oplus 0_{m?r}]U^{?},\text{for any}n\times n\text{Hermitian}A\text{with rational trace}.$ We also extend this result to the (complex) von Neumann algebra setting, and provide a supplement to the Dye-Bunce-Wright Theorem asserting that every additive map of Hermitian idempotents extends to a Jordan ?-homomorphism.     

On weighted spectral radius of unraveled balls and normalized Laplacian eigenvalues

For a graph G, the unraveled ball of radius r centered at a vertex v is the ball of radius r centered at v in the universal cover of G. We obtain a lower bound on the weighted spectral radius of unraveled balls of fixed radius in a graph with positive weights on edges, which is used to present an upper bound on the $s^{\text{th}}$ (where $s\ge 2$) smallest normalized Laplacian eigenvalue of irregular graphs under minor assumptions. Moreover, when $s=2$, the result may be regarded as an Alon–Boppana type bound for a class of irregular graphs.     

Stability of Multiplier Ideal Sheaves

Chinese Annals of Mathematics, Series B - In the present article, the authors find and establish stability of multiplier ideal sheaves, which is more general than strong openness.     

现代分析仪器在高中化学教学中的应用*——以“防晒霜的防晒效果实验探究”为例

从高中化学原子、分子等抽象性的知识教学出发,以防晒霜的防晒效果实验探究为例,探讨了现代分析仪器在高中化学教学中的应用。通过利用现代分析仪器紫外可见分光光度计,结合紫外线变色球实验探究防晒霜的防晒效果,分析并认识防晒霜中化学防晒的机理。结果表明,防晒霜的厚度越大、SPF越高,防晒霜的防晒效果越好,并且防晒霜的防晒效果可以持续一段时间,但是不同类型的防晒产品存在一定差异。在化学教学中渗透现代分析仪器的应用,为学生进一步了解化学学科在改变学习方式、拓宽学科知识领域、推动自身全面与可持续发展方面打下坚实的基础。