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521.
Based on the principle of virtual work, an updated Lagrangian finite element formulation for the geometrical large deformation analysis of galloping of the iced conductor in an overhead transmission line is developed. In numerical simulation, a three-node isoparametric cable element with three translational and one torsional degrees-of-freedom at each node is used to discretize the transmission line. The nonlinear dynamic system equation is solved with the Newmark time integration method and the Newton-Raphson nonlinear iteration. Numerical examples demonstrate the efficiency of the presented method and the developed finite element program. A new possible galloping mode, which may reflect the saturation phenomenon of a nonlinear dynamic system, is discovered under the condition that the lowest order of vertical natural frequency of the transmission line is approximately two times of the horizontal one. 相似文献
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523.
Nishio Keishi Okubo Koji Watanabe Yuichi Tsuchiya Toshio 《Journal of Sol-Gel Science and Technology》2000,19(1-3):187-191
Organic-inorganic hybrid lithium ion conductors were prepared by the sol-gel process. The hybrid ion conductor will be used as the electrolyte for Li based high-energy density batteries. The hybrid ion conductor was prepared from a mixture of tetramethyl orthosilicate (TMOS), polyethylene glycol 200 (PEG200), lithium perchlorate (LiClO4) and water. A wet gel was prepared at room temperature. The gels dried at 80°C under vacuum did not contain water. The dried hybrid ion conductor gel had homogeneity and high transparency. Ionic conductivity of the hybrid sample was measured by the complex impedance method and it increased with increasing PEG200 content. The dried hybrid gel that contained no LiClO4 did not show ion conduction. Conductivity on the order of 10–5 S·cm–1 at room temperature was obtained. Structural characterization was done by Fourier Transform Infrared Spectra (FTIR) and NMR measurement of 13C and 1H, and the thermal stability and glass transition properties were studied by DSC. Glass transition temperature decreased with increasing PEG200 content and increased with increasing [Li]/[O] ratio (the oxygen considered is from the polyethylene glycol). Existence of the Si–O–(C2H4O)
n
–bond and the C–OH bond in the framework of the organic and inorganic phases was confirmed. TMOS and PEG200 were hydrolyzed and condensed. The organic and inorganic phases were chemically bonded and the microstructure of the hybrid matrix was shaped as comb. The comb shape leads to high ionic conduction. 相似文献
524.
The high temperature structure above 700 °C of the oxygen superionic conductor La0.9Sr0.1Ga0.8Mg0.2O2.85 has been analyzed by means of a combined neutron and high resolution synchrotron powder study. The splitting of reflections and the absence of any superstructure reflections leads to the conclusion that the correct space group is R3¯m. This is the first example of this space group appearing within the subgroup family of the ideal parent perovskite structure with Pm3¯m symmetry. 相似文献
525.
The electrical conduction behavior of SrCe0.95Tb0.05O3−δ (SCTb) was investigated in different gases at high temperatures. In air, oxygen or nitrogen SCTb shows small electronic-hole conduction below 800°C and oxygen ionic conduction over 800°C with activation energy about 30 kJ/mol and 164–181 kJ/mol respectively. SCTb becomes a protonic conductor in hydrogen or methane in 500–900°C, with the proton conductivity in the range of 10−3–10−2 S/cm, two to three orders of magnitude higher than electronic or oxygen ionic conductivity of SCTb in air or oxygen. The activation energy for protonic conduction in SCTb is 49 kJ/mol in methane and 54 kJ/mol in hydrogen. The electrical conductivity of SCTb in water vapor-saturated nitrogen, air or oxygen is higher than in corresponding gas without water vapor. Presence of water vapor does not affect the electrical conduction of SCTb in hydrogen or methane. Gas permeation measurements show that SCTb membrane is impermeable to hydrogen when the membrane is exposed to hydrogen or methane upstream and nitrogen or oxygen downstream. These results confirm that SCTb is a pure protonic conductor with very low electronic and oxygen ionic conductivity. SCTb will find applications as a high temperature electrolyte in fuel cells or hydrogen sensors. 相似文献
526.
传统的载流细导体段模型是分析导体闭合回路磁场的基本模型,尽管不满足电流连续性定律,但适用于导体闭合回路的磁场分析.然而,对于工程中只关注导体闭合回路中某一局部的多分支导体段并联的电流分配问题,传统模型将不能完整地反映各分支导体段之间磁场的相互作用.为此,现有文献提出的位移电流模型,满足了电流连续性定律,较好地解决了上述问题,但是,仍然存在理论不完整、不自洽以及计算公式复杂等问题.本文提出载流细导体段的传导电流模型,确保了载流细导体段在段内、段端及段外的电流连续性.推导出物理内涵更加深刻的总磁场微分方程和矢量磁位计算公式.提出载流细导体段传导电流模型磁场能量和电感的计算公式,极大地降低了计算复杂度,弥补了现有文献的不足.本文算例从模型、公式、计算等方面验证了本文理论和计算公式的正确性. 相似文献
527.
528.
采用溶胶-凝胶技术研究了ZrOCl2·8H2O掺杂对磷硅酸盐凝胶质子导电性能的影响. 结果表明, 掺杂ZrOCl2·8H2O能提高磷硅酸盐凝胶的质子电导率, 并且掺杂质量分数为0.97%时质子电导率达到最大值(σ130=2.38 S/m). 掺杂样品在相对湿度为40%条件下放置30 d后, 未发生H3PO4渗出现象, 其质子传导性能基本不变. 核磁共振谱结果表明, 掺杂ZrOCl2减少了磷硅酸盐凝胶结构中自由磷酸的形成, 提高了与四面体之间的化学结合力. 相似文献
529.
Ce(SO4)2-doped phosphosilicate gel was prepared by mechanical milling.Complex impedance analysis proved that the 15 h-ball-milled sample showed a maximum conductivity of 2.97 S/m at 130 ℃,which is abou... 相似文献
530.