大功率高温超导滤波器的设计与功率测试

本文在双面YBCO高温超导薄膜上设计并制备了两节大功率超导滤波器,根据滤波器功率承载能力与最大电流密度之间的关系,减小电流密度和分散电流密度的分布是提高功率承载能力的关键.本文采用增加超导谐振器尺寸、优化几何结构及改进馈线耦合方式的方法,设计了两节2 GHz频段梭型谐振器结构的滤波器.设计及测量结果显示了馈线结构及谐振器几何尺寸优化程度对超导滤波器功率承载能力有不同程度的影响,说明了在大功率超导滤波器设计中应选用无结点间隙耦合式馈线以抑制电流密度的聚集.采用优化后的谐振器结构制备的梭型两节超导滤波器经测试功率承载能力为2 W.超导滤波器的尺寸为25×12 mm LaAlO3基片,中心频率2.022 GHz,相对带宽为2.4%.同时给出了超导滤波器功率测试的结构和方法.     

Optimizing thermography depth probing with a dynamic thermal point spread function

Derivation of two point spread functions PSFs suitable for infrared thermograms analysis is illustrated, based on two unique approaches, one based on depth decaying limit and one on diffusion limit. Experimental work using PMMA sample with back drilled holes and pulsed thermographic routine is utilized to show the effectiveness of deconvoluting pixel temperature transient history with suggested PSF’s. Synthetic second time derivative thermograms are utilized for comparison and the signal to noise ratio is used as a figure of merit for quantification.     

Creation of helical vortices during magnetization of aligned carbon nanotubes filled with Fe: theory and experiment

We report a novel magnetic phenomenon consisting of the formation of helical spin configurations during the magnetization of densely packed ferromagnetic nanowires encapsulated inside carbon nanotubes. We studied the hysteresis loops when the magnetic fields are applied parallel and perpendicular to the nanotubes axes. We also performed theoretical calculations on aligned nanowire arrays that clearly indicate the creation of helical spin vortices in the hysteresis loops. The latter are caused by the presence of strong dipolar interactions among neighboring wires.     

高温超导滤波器的光刻工艺

根据高温超导薄膜的特点,详细讨论了制备高温超导滤波器的光刻技术及在制备的各环节中需注意的问题,实验结果表明:此种方法提高了制备的成功率。     

Theoretical study of the electronic structure of LiNa and LiNa<Superscript>+</Superscript> molecules

Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels of the lowest electronic states of the alkali dimer LiNa molecule dissociating into Na (3s, 3p, 4s, 3d, and 4p) + Li (2s, 2p, 3s, and 3p) in ^1,3Σ, ^1,3Π, and ^1,3Δ symmetries are presented. Adiabatic results are also reported for ²Σ, ²Π, and ²Δ electronic states of the molecular ion LiNa⁺ dissociating into Li (2s, 2p, 3s, and 3p) + Na⁺ and Li⁺  + Na(3s, 3p, 4s, 3d, and 4p). We use an ab initio approach involving a non-empirical pseudopotential for the Li (1s²) and Na (1s²2s²2p⁶) cores and core valence correlation correction. A very good agreement is obtained for some lowest states of the LiNa and LiNa⁺ molecules for spectroscopic constants with the available theoretical works. The existence of numerous avoided crossings between electronic states of ²Σ and ²Π symmetries is related to the charge transfer process between the two ionic systems Li⁺Na and LiNa⁺.     

电流模式SEPIC变换器倍周期分岔现象研究

以SEPIC变换器中前置电感电流为控制对象,建立了SEPIC变换器断续电流模式下的离散时间模型, 并分析了不动点的稳定性.通过相轨图、功率谱图以及分岔图, 发现电路中存在一种特殊的倍周期分岔现象——电路的运行状态经历了1倍周期、 2倍周期、4倍周期再到2倍周期、4倍周期,最终进入混沌状态.实验结果与仿真结果相一致, 证实了SEPIC变换器在断续电流模式下存在这种倍周期分岔现象.     

Hidden-gauge model and radiative decays

We consider the radiative decay widths in a hidden-gauge model. For calculating the decay widths we use the anomalousVVP Lagrangian.g _VVP is a function off _P due to the symmetry breaking effects. It is shown thatf _P is consistent with that obtained by the one-loop calculation. A reasonable agreement with the experimental decay widths is achieved.     

高温超导滤波器两种刻蚀方法的研究

在高温超导滤波器的制备过程中,针对所使用的高温超导薄膜的特点,采用了两种刻蚀方法——湿化学刻蚀法和离子束刻蚀法,设计对比了两种刻蚀的制作流程及其优缺点,并用两种方法分别制备了高温超导滤波器,对微波特性做了对比分析。得出离子束刻蚀对超导薄膜的性能影响要小一些,用此方法制备的高温超导滤波器具有更好的微波特性。     

A high-order discontinuous Galerkin method for wave propagation through coupled elastic–acoustic media

We introduce a high-order discontinuous Galerkin (dG) scheme for the numerical solution of three-dimensional (3D) wave propagation problems in coupled elastic–acoustic media. A velocity–strain formulation is used, which allows for the solution of the acoustic and elastic wave equations within the same unified framework. Careful attention is directed at the derivation of a numerical flux that preserves high-order accuracy in the presence of material discontinuities, including elastic–acoustic interfaces. Explicit expressions for the 3D upwind numerical flux, derived as an exact solution for the relevant Riemann problem, are provided. The method supports h-non-conforming meshes, which are particularly effective at allowing local adaptation of the mesh size to resolve strong contrasts in the local wavelength, as well as dynamic adaptivity to track solution features. The use of high-order elements controls numerical dispersion, enabling propagation over many wave periods. We prove consistency and stability of the proposed dG scheme. To study the numerical accuracy and convergence of the proposed method, we compare against analytical solutions for wave propagation problems with interfaces, including Rayleigh, Lamb, Scholte, and Stoneley waves as well as plane waves impinging on an elastic–acoustic interface. Spectral rates of convergence are demonstrated for these problems, which include a non-conforming mesh case. Finally, we present scalability results for a parallel implementation of the proposed high-order dG scheme for large-scale seismic wave propagation in a simplified earth model, demonstrating high parallel efficiency for strong scaling to the full size of the Jaguar Cray XT5 supercomputer.     

便携式多源光谱融合水质分析仪的研制

采用光谱信息融合理论,研制了一种新型便携式多参数水质分析仪,自行设计了仪器的分析方法、硬件结构、内部工作原理及软件功能.可作为一种无须化学试剂、体积小、快速、易于野外现场作业的绿色水质检测工具.通过对少量水质样品的光谱测量分析,快速检测了总有机碳(TOC)、化学需氧最(COD)等6类水质有机污染物指标.实际测量结果表明,本仪器采用的基于多源光谱信息融合的水质分析方法测量精度显著优于目前市场上普遍采用的常规紫外吸收光谱法.