Influence of Fe-doping on the microstructure and electromagnetic performance of manganese oxides

A simple wet chemical method was used to synthesize Fe-doped MnO₂ composites with iron amount ranging from 0 to 90 M percent. X-ray diffraction, electron probe micro-analyzer, scanning electron microscopy and vector network analyzer were employed to investigate the effect of iron doping on the microstructure and electromagnetic performance of the as-synthesized samples. Results indicate that relative small content of Fe-doping cannot change the α-MnO₂ structure but can promote the formation of hollow-structural morphology. The as-obtained products are transformed into a novel compound (Fe_0.67Mn_0.33)OOH with the increase of Fe-doping to 30 mol%. The possible formation mechanism was proposed in detail. Compared with the pure MnO₂, the Fe-doped samples exhibit decreased dielectric loss but increased magnetic loss with increasing the iron content below 20 mol% while relatively poor electromagnetic properties with the iron content above 30 mol%.     

等离子体羽中氧原子的光谱强度分布

大气压等离子体羽放电产生的低温等离子体由于不需要真空装置,可以对复杂材料进行三维处理等,在工业上具有广泛的应用前景。本工作利用等离子体针放电装置在大气压空气中产生了稳定的等离子体羽。通过光谱测量,发现等离子体羽发射谱中存在777.5和844.6nm的氧原子谱线。这表明在大气压空气放电中产生了具有高化学活性的氧原子。通过光谱学方法研究了氧原子谱线强度的空间分布,发现靠近电极处氧原子谱线强度远大于其他位置。为了对这一现象进行解释,利用光电倍增管对等离子体羽的发光信号进行了空间分辨测量,发现靠近电极处发光信号宽度远大于其他位置的发光信号宽度。这些结果对大气压空气等离子体羽在杀菌消毒等领域的应用具有重要意义。     

Observation of multiple higher-order stopgaps from three-dimensional chalcogenide glass photonic crystals

For the first time to our knowledge the observation of near-IR multiple higher-order stopgaps in three-dimensional photonic crystals (PhCs) fabricated using the direct-laser-writing method in thick chalcogenide glass films is reported. The fabrication and etching conditions necessary to realize well-defined structures are presented. The fabricated PhCs exhibit higher-order stopgaps, which are only evident in high-quality structures. The higher-order stopgaps observed permit these high-refractive-index and high-nonlinear PhCs to be used directly as functional photonic devices operating at telecommunication wavelengths without further miniaturizing structural dimensions.     

A new high-order discontinuous Galerkin spectral finite element method for Lagrangian gas dynamics in two-dimensions

This paper presents a new high-order cell-centered Lagrangian scheme for two-dimensional compressible flow. The scheme uses a fully Lagrangian form of the gas dynamics equations, which is a weakly hyperbolic system of conservation laws. The system of equations is discretized in the Lagrangian space by discontinuous Galerkin method using a spectral basis. The vertex velocities and the numerical fluxes through the cell interfaces are computed consistently in the Eulerian space by virtue of an improved nodal solver. The nodal solver uses the HLLC approximate Riemann solver to compute the velocities of the vertex. The time marching is implemented by a class of TVD Runge–Kutta type methods. A new HWENO (Hermite WENO) reconstruction algorithm is developed and used as limiters for RKDG methods to maintain compactness of RKDG methods. The scheme is conservative for the mass, momentum and total energy. It can maintain high-order accuracy both in space and time, obey the geometrical conservation law, and achieve at least second order accuracy on quadrilateral meshes. Results of some numerical tests are presented to demonstrate the accuracy and the robustness of the scheme.     

A note on the area spectrum of d-dimensional pure de Sitter Space-time

Consistent supercurrent multiplets are naturally associated with linearized off-shell supergravity models. In S.M. Kuzenko, J. High Energy Phys. 1004, 022 (2010) we presented the hierarchy of such supercurrents which correspond to all the models for linearized 4D $\mathcal{N}=1$ supergravity classified a few years ago. Here we analyze the correspondence between the most general supercurrent given in S.M. Kuzenko, J. High Energy Phys. 1004, 022 (2010) and the one obtained eight years ago in M. Magro et al., Ann. Phys. 298, 123 (2002) using the superfield Noether procedure. We apply the Noether procedure to the general $\mathcal{N}=1$ supersymmetric nonlinear sigma-model and show that it naturally leads to the so-called $\mathcal{S}$ -multiplet, revitalized in Z. Komargodski, N. Seiberg, J. High Energy Phys. 1007, 017 (2010).     

Dynamic single-mode and modulation characteristics analyses for λ/4 phase-shifted distributed feedback lasers with chirped grating

The dynamic single-mode and modulation performance of λ/4 phase-shifted distributed feedback laser diode with chirped grating (QWS-CG-DFB) are analyzed theoretically. The numerical simulation shows that, in contrast to purely QWS-DFB laser, the enhanced dynamic single-mode suppression ratio (SMSR) can be reached by QWS-CG-DFB laser. Under the smaller biasing current, the modulation band-width in presence of chirped grating is narrower, this difference shrinks for larger biasing current. For large signal modulation, the chirped grating is helpful to increase the output extinction ratio, but worsens the frequency chirping. The good dynamic characteristic can be obtained by selecting system parameters reasonably.     

恒温恒湿空调三种工况下自动控制研究

针对恒温恒湿空调在夏季、冬季和过渡季节三种典型工况下的自动控制,详细分析了三种工况下空气处理过程,对温度和湿度的控制进行了分解、给出了实现框图并分析了控制系统本身造成的控制精度问题,为恒温恒湿空调的控制改进提供参考。     

Fuzzy Matching Based on Gray-scale Difference for Quantum Images

Quantum image processing has recently emerged as an essential problem in practical tasks, e.g. real-time image matching. Previous studies have shown that the superposition and entanglement of quantum can greatly improve the efficiency of complex image processing. In this paper, a fuzzy quantum image matching scheme based on gray-scale difference is proposed to find out the target region in a reference image, which is very similar to the template image. Firstly, we employ the proposed enhanced quantum representation (NEQR) to store digital images. Then some certain quantum operations are used to evaluate the gray-scale difference between two quantum images by thresholding. If all of the obtained gray-scale differences are not greater than the threshold value, it indicates a successful fuzzy matching of quantum images. Theoretical analysis and experiments show that the proposed scheme performs fuzzy matching at a low cost and also enables exponentially significant speedup via quantum parallel computation.     

Control of Quantum Echo and Bell State Swapping of Two Atomic Qubits in the Two-Mode Vacuum Field Environment

We investigate quantum echo control and Bell state swapping for two atomic qubits (TAQs) coupling to two-mode vacuum cavity field (TMVCF) environment via two-photon resonance. We discuss the effect of initial entanglement factor ?? and relative coupling strength R=g₁/g₂ on quantum state fidelity of TAQs, and analyze the relation between three kinds of quantum entanglement(C(ρ_a),C(ρ_f),S(ρ_a)) and quantum state fidelity, then reveal physical essence of quantum echo of TAQs. It is shown that in the identical coupling case R=1, periodic quantum echo of TAQs with π cycle is always produced, and the value of fidelity can be controlled by choosing appropriate ?? and atom-filed interaction time. In the non-identical coupling case R≠1, quantum echoes with periods of π, 2π and 4π can be formed respectively by adjusting R. The characteristics of quantum echo results from the non-Markovianity of TMVCF environment, and then we propose Bell state swapping scheme between TAQs and two-mode cavity field.