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1.
双包层椭圆光波导解析解 总被引:3,自引:0,他引:3
解析求解了双包层椭圆光纤中的波动方程,得到了模式精确解有模式特征方程。对基模的特征方程进行了数值计算,给出了不同椭圆比下的归一化双折射和模间色散随归一化频率的变化关系曲线,并与高斯近似解的结果进行了比较。 相似文献
2.
The first MCM-41-supported bidentate phosphine palladium(0) complex has been prepared. This complex is a highly efficient catalyst for Sonogashira reaction and can be reused at least 10 times without any decrease in activity. 相似文献
3.
Qiuhua Liang 《国际流体数值方法杂志》2012,69(2):442-458
This paper presents a new simplified grid system that provides local refinement and dynamic adaptation for solving the 2D shallow water equations (SWEs). Local refinement is realized by simply specifying different subdivision levels to the cells on a background uniform coarse grid that covers the computational domain. On such a non‐uniform grid, the structured property of a regular Cartesian mesh is maintained and neighbor information is determined by simple algebraic relationships, i.e. data structure becomes unnecessary. Dynamic grid adaptation is achieved by changing the subdivision level of a background cell. Therefore, grid generation and adaptation is greatly simplified and straightforward to implement. The new adaptive grid‐based SWE solver is tested by applying it to simulate three idealized test cases and promising results are obtained. The new grid system offers a simplified alternative to the existing approaches for providing adaptive mesh refinement in computational fluid dynamics. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
4.
Meng Sun Xiaoxing Ma Juntao Wang Weina Wang Qiuhua Wu Chun Wang Zhi Wang 《Journal of separation science》2013,36(8):1478-1485
In this paper, a novel graphene (G) grafted silica‐coated Fe3O4 nanocomposite was fabricated by the chemical bonding of G onto the surface of silica‐coated Fe3O4 nanoparticles. Some carbamates (metolcarb, carbaryl, pirimicarb, and diethofencarb) in cucumber and pear samples were enriched by this nanocomposite prior to their determination by HPLC with UV detection. Experimental parameters that may affect the extraction efficiency were investigated. Under the optimum conditions, a linear response was achieved in the concentration range of 0.5–100.0 ng/g for metolcarb, carbaryl, and diethofencarb, and 1.0–100 ng/g for pirimicarb with the correlation coefficients (r) ranging from 0.9956 to 0.9984. The LOD (S/N = 3) of the method were found to be in the range from 0.08 to 0.2 ng/g. The RSDs were in the range from 2.4 to 5.8%. The results indicated that the G grafted silica‐coated Fe3O4 nanocomposite was stable and efficient for magnetic SPE and has a great application potential for the preconcentration of other organic pollutants from real samples. 相似文献
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在一定条件下,精胺不仅能够与脱氧核糖核酸(DNA)大沟嵌入结合,还能与DNA链上的碱基和磷酸基进行链内结合和跨链结合,形成致密的环状螺旋结构,造成DNA的凝聚,从而使DNA共振光散射(RLS)强度强烈地增强。增强的共振光散射强度与精胺的浓度呈现良好的线性关系,线性范围为5.0×10-7~1.0×10-5mol/L;校正曲线的回归方程为IRLS=40.22 5.28×107C(mol/L),相关系数r=0.9936;检出限(3σ)为7.4×10-8mol/L。在测定精胺的线性范围内,其它多胺(亚精胺,腐胺)、蛋白质及常见的金属离子不干扰测定。该方法用于测定新几内亚凤仙中的精胺,获得满意结果。 相似文献
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Qiuhua Nie Tiefeng Xu Xiang shen Xudong Zhang 《Journal of Physics and Chemistry of Solids》2006,67(11):2345-2350
The absorption and upconversion fluorescence spectra of a series of Er3+/Yb3+-codoped natrium-germanium-bismuth glasses have been studied. The transition probabilities, excited state lifetimes, and the branching ratios have been predicted for Er3+ based on the Judd-Ofelt theory. At room temperature, an upconversion efficiency of 6.1×10−2 has been obtained for the green emission from the glass with 0.5 wt% Er2O3 and 3.0 wt% Yb2O3 pumped by 980 nm radiation with an intensity of 270 W/cm2. And the “standardized” efficiency for green upconversion light is higher than that reported in lead-germanate, lead-tellurite-germanate, and silicate glasses. The results indicate that the Er3+/Yb3+-codoped natrium-germanium-bismuth oxide glass may be a potential material for developing upconversion optic devices. 相似文献
9.
Changshen Yi Peiqing Zhang Feifei Chen Shixun Dai Xunsi Wang Tiefeng Xu Qiuhua Nie 《Applied physics. B, Lasers and optics》2014,116(3):653-658
Chalcogenide glasses are known for their high transparency in the mid-infrared (IR) range, which includes two atmospheric windows that lie from 3 to 5 μm and 8 to 12 μm, respectively. Chalcogenide photonic crystal fibers have numerous potential applications in the field of IR, such as spectroscopy, microscopy, astronomy, biology, and sensing. In this paper, Ge20Sb15S65 chalcogenide glass was fabricated and systematically studied. Chalcogenide glass has high transmission property (>70 %), good thermal stability, and good mechanical stability. The glass transition temperature T g is 296 °C, and no exothermic peak was associated with crystallization up to 500 °C, which indicates its suitability for fiber drawing. As a result of its excellent mechanical properties, preforms with a variety of geometrical patterns were fabricated by using mechanical drilling. The near-field intensity distribution image of the drawn fiber shows a strong light propagation confinement. 相似文献
10.
Guoxiang Wang Qiuhua Nie Xiang Shen Xunsi Wang Fen Chen Shixun Dai Tiefeng Xu 《Infrared Physics & Technology》2012,55(4):275-278
A systematic series of (Ge20Se15Te65)1?x–(SnI2)x (x = 0, 0.05, 0.1, 0.15) chalcogenide glasses have been prepared. The amorphous nature can be confirmed by XRD and SEM. With the SnI2 content increasing, the indirect optical band gaps are decreased from 0.662 to 0.622 eV according to Tauc laws. The introduction of SnI2 makes the glasses much easier to prepare and more stable against crystallization, making them drawable as optical fibers. The highest ΔT (130 °C) value for (Ge20Se15Te65)0.9–(SnI2)0.1 glass composition can be obtained. A slight red-shifting of the long-wavelength cutting-off edge from 18.4 to 19.4 μm was shown and it seems that SnI2 in these glasses offers the improvement in the far-infrared properties. 相似文献