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排序方式: 共有129条查询结果,搜索用时 15 毫秒
61.
Hassan Fahs Stéphane Lanteri 《Journal of Computational and Applied Mathematics》2010,234(4):1088-1096
In this paper, we discuss the formulation, stability and validation of a high-order non-dissipative discontinuous Galerkin (DG) method for solving Maxwell’s equations on non-conforming simplex meshes. The proposed method combines a centered approximation for the numerical fluxes at inter element boundaries, with either a second-order or a fourth-order leap-frog time integration scheme. Moreover, the interpolation degree is defined at the element level and the mesh is refined locally in a non-conforming way resulting in arbitrary-level hanging nodes. The method is proved to be stable and conserves a discrete counterpart of the electromagnetic energy for metallic cavities. Numerical experiments with high-order elements show the potential of the method. 相似文献
62.
Summary: This article describes the development and evolution of two-photon lithography of 3-dimensional (3D) polymeric structures through two-photon photopolymerization (TPP) and the materials used to facilitate the same. The first part elaborates on the advantages of TPP over conventional lithographic techniques used in the fabrication of 3D microelectromechanical systems (MEMS). The second part introduces the preparation of highly efficient organic two-photon absorbing materials based on the centro-symmetric π-conjugated system and their performance as sensitizers in two-photon polymerization. 相似文献
63.
Andreea Ionescu Rossella Caligiuri Nicolas Godbert Angela Candreva Massimo LaDeda Emilia Furia Mauro Ghedini Iolinda Aiello 《化学:亚洲杂志》2019,14(17):3025-3034
A series of electropolymerizable cyclometallated IrIII complexes were synthesized and their electrochemical and photophysical properties studied. The triphenylamine electropolymerizable fragment was introduced by using triphenylamine‐2‐phenylpyridine and, respectively, triphenylamine‐benzothiazole as cyclometalated ligands. The coordination sphere was completed by two differently substituted β‐ketoiminate ligands deriving from the condensation of acetylacetone or hexafluoroacetylacetone with para‐bromoaniline. The influence of the ‐CH3/‐CF3 substitution to the electrochemical and photophysical properties was investigated. Both complexes with CH3 substituted β‐ketoiminate were emissive in solution and in solid state. Highly stable films were electrodeposited onto ITO coated glass substrates. Their emission was quenched by electron trapping within the polymeric network as proven by electrochemical studies. The ‐CF3 substitution of the β‐ketoiminate leads instead to the quenching of the emission and inhibits electropolymerization. 相似文献
64.
Robert Infuehr Niklas Pucher Christian Heller Helga Lichtenegger Volker Schmidt Anja Haase 《Applied Surface Science》2007,254(4):836-840
In the presented work, two-photon 3D lithography and selective single-photon photopolymerization in a prefabricated polydimethylsiloxane matrix is presented as an approach with potential applicability of waveguide writing in 3D by two-photon polymerization.Photopolymers based on acrylate chemistry were used in order to evaluate the optical capabilities of the available two-photon system. Several photoinitiators, tailored for two-photon absorption, were tested in a mixture of trimethylolpropane triacrylate and ethoxylated trimethylolpropane triacrylate. Best results were obtained with a recently synthesized diynone-based photoinitiator. Feature resolutions in the range of 300 nm were achieved. Due to the cross-conjugated nature of that donor-π-acceptor-π-donor system a high two-photon absorption activity was achieved. Therefore, a resin mixture containing only 0.025 wt% of photoinitiator was practical for structuring by two-photon polymerization. The required initiator content was therefore a factor of 100 lower than in traditional one-photon lithography.The aim of the second part of this work was to fabricate optical waveguides by selectively irradiating a polymer network, which was swollen by a monomer. The monomer was polymerized by conventional single-photon polymerization and the uncured monomer was removed by evaporation at elevated temperatures. This treatment leads to a local change in refractive index. Refractive index changes in the range of Δn = 0.01 (Δn/n = 0.7%) were achieved, which is sufficient for structuring waveguides for optoelectronic applications. 相似文献
65.
E. V. Bekker A. Vukovic P. Sewell T. M. Benson N. K. Sakhnenko A. G. Nerukh 《Optical and Quantum Electronics》2007,39(7):533-551
This paper presents an analytical methodology for analysing two-dimensional, dielectric slab waveguides where the guiding
region is subject to abrupt and arbitrary temporal changes in permittivity. The methodology solves Maxwell’s equations in
the frequency domain and recovers the solutions for the guided and radiation fields in the time domain using the Laplace transformation
(LT). Explicit separation of the complete field solution into a set of guided modes and a radiation field continuum provides
a clearer insight into the transient effects present in time-varying dielectric waveguides. In particular, the method is used
to assess and quantify the impact of coherent radiation field coupling for arbitrary time variation of the waveguide permittivity. 相似文献
66.
The refractive index of a dielectric medium comprising both passive and inverted components in its permittivity was determined using two methods: (i) in the time-domain, a finite-difference algorithm to compute the frequency-domain reflectance from reflection data for a pulsed plane wave that is normally incident on a dielectric half-space and (ii) in the frequency-domain, the deflection of an obliquely incident Gaussian beam on transmission through a dielectric slab. The dielectric medium was found to be an active medium with a negative real part for its refractive index. Thereby, a recent controversy in the scientific literature was resolved. 相似文献
67.
采用DFT/B3LYP/6-31G*和ZINDO-SOS方法, 系统地研究了两个系列(以苯为中心的a系列和以三苯胺为中心的b系列)星型准八极矩分子及其单枝物的单光子和双光子吸收性质. 结果表明, b系列分子有较大的双光子吸收截面和更长的单光子和双光子吸收波长. 星型三分枝分子的双光子吸收截面较其单个分枝增长了超过3倍因为存在分枝间的相互作用. 含1,3,4-噁二唑的分子比含2,1,3-苯并噻二唑的分子有更大的双光子吸收截面但是最大吸收波长却蓝移, 不在红外或近红外区域. 相似文献
68.
69.
用太赫兹(THz)时域光谱技术研究了室温条件下的萘醌及其衍生物1,2-萘醌、1,2-萘醌-4-磺酸钠、甲萘醌、白花丹素、胡桃醌的光谱特征,得到了各自的吸收谱和折射率。结果表明,萘醌及其衍生物在此波段有不同的吸收特征,利用太赫兹时域光谱能够鉴别分子结构存在微小差别的化合物。在对样品的吸收谱进行比较的基础上,讨论了分子结构和分子间晶格振动与THz光谱特征吸收的关系。 相似文献
70.
A 1D finite element method in time domain is developed in this paper and applied to calculate in-plane wave motions of free
field exited by SV or P wave oblique incidence in an elastic layered half-space. First, the layered half-space is discretized
on the basis of the propagation characteristic of elastic wave according to the Snell law. Then, the finite element method
with lumped mass and the central difference method are incorporated to establish 2D wave motion equations, which can be transformed
into 1D equations by discretization principle and explicit finite element method. By solving the 1D equations, the displacements
of nodes in any vertical line can be obtained, and the wave motions in layered half-space are finally determined based on
the characteristic of traveling wave. Both the theoretical analysis and the numerical results demonstrate that the proposed
method has high accuracy and good stability.
The project supported by the National Natural Science Foundation of China (50478014), the National 973 Program (2007CB714200)
and the Beijing Natural Science Foundation (8061003).
The English text was polished by Yunming Chen. 相似文献