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Considerable irreversible capacity loss was observed after the electrode standing at small state-of-charge (SOC) for only a short term. Influence of SOC, standing time and the replacement elements of LaNi5-type hydrogen storage alloys to standing was discussed. Charge-transfer resistance, exchange current density (I0 ), and hydrogen diffusion coefficient were determined based on the study of electrochemical impedance spectrum (EIS), linear polarization (LP) and constant potential step (CPS), respectively. The oxidation of metal Ni on the alloy surface after standing was responsible for the rapid deterioration of capacity, charge-transfer resistance and I0 . Galvanostatic, LP, EIS and CPS measurements suggested the presence of an oxide and/or corrosion layer on the alloy surface of raw material and electrode after standing at 0% SOC for 2 d. It was proved that the first small semicircle in high-frequency region of EIS was related to this layer. Novel EIS model in metal hydride electrode was proposed accordingly. 相似文献
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目的 针对传统乌鸦算法随机搜索的盲目性和易陷入局部最优的缺点,提出一种改进乌鸦算法,用于多阈值图像分割.方法 采用精英分享策略,弥补乌鸦位置更新的盲目性;引入Levy飞行机制,避免算法陷入局部最优;随迭代次数调整变尺度系数,限制搜索步长,加快算法收敛;以Kapur熵为适应函数,利用改进乌鸦算法对不同类型图像进行多阈值分割,并与传统乌鸦、布谷鸟等4种算法的分割结果进行对比分析.结果 改进乌鸦算法对Lena,Flower,Fruits和Boat图分割后的结构相似性分别为0.7703,0.7761,0.7276和0.7921;标准偏差分别为0.0295,0.0385,0.0344和0.0173,实验数据表明,改进算法较其他算法有着更好的分割效果.结论 文中算法有效地改进了传统乌鸦算法的盲目性和易陷入局部最优的缺点,能够准确地分割复杂图像,在多阈值图像分割领域具有一定的参考价值. 相似文献
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强加阳极电流的方法被广泛应用于钢筋的人工加速腐蚀,但串联或并联形式加速腐蚀电路往往由于电流分布的差异导致钢筋腐蚀程度不均匀。为了优化强加阳极电流的钢筋加速腐蚀方法,提出了一种多向式的混合连接电路形式并开展钢筋加速腐蚀试验,对比分析了混合连接、串联、并联3种加速腐蚀模式下,各组钢筋试件的电流情况、腐蚀电位与腐蚀电流密度的变化、腐蚀率以及腐蚀产物情况。结果显示,串联和并联电路形式中钢筋的电流分布存在差异导致钢筋腐蚀程度不一致;混合连接形式中,电流分布均匀且钢筋表面腐蚀程度相近,各钢筋试件锈蚀率接近理论值。通过多向式的混合连接电路可以实现均匀加速腐蚀钢筋或钢筋混凝土构件,有效优化了钢筋加速腐蚀的效果,为加速腐蚀钢筋或钢筋混凝土构件提供了参考。 相似文献