悬臂浇筑法中劲性骨架段的合理长度

悬臂浇筑与劲性骨架组合施工法是一种新型的钢筋混凝土拱桥施工方法,相较于悬臂浇筑施工,不仅可以缩短拱圈悬臂浇筑段的长度,减轻悬臂的质量,降低对扣锚系统的要求,而且能够尽快形成拱结构,从而减少施工风险,缩短工期,提高钢筋混凝土拱桥的经济性。从主拱圈自身受力特点、扣索力的利用效率、施工过程最大扣索力、拱圈拉应力等几个方面分析了悬臂浇筑与劲性骨架组合法中劲性骨架段合理长度的选取。结果表明劲性骨架段长度取跨度的0. 38～0. 54倍最为合理。     

镁合金进气歧管消失模铸造工艺的试验初探

探索了AZ91镁合金发动机进气歧管的消失模铸造工艺，分析了镁合金的工艺特点，认为消失模铸造工艺用于镁合金材质发动机进气歧管在技术上是可行的。     

Effect of La addition on electrochemical properties of amorphous LaMg11Zr+200Ni alloy

The effect of La addition on the structure and electrochemical properties of amorphous LaMg₁₁Zr+200Ni (LaMg₁₁Zr: Ni = 1: 2, m: m) hydrogen storage alloy prepared by mechanical alloying was investigated systematically. The results show that the alloys have an amorphous structure after 20 h ball-milling and the particles are significantly refined with the addition of La. The electrochemical tests indicate that the charging resistance of the alloy electrodes decreases with the addition of La. The maximum discharge capacity of the alloy electrodes increases with the increase of La addition, while the cyclic stability and high-rate discharge performance increase firstly and then decrease as the La content increases. When the mass fraction of La is up to 5%, the maximum discharge capacity after charging/discharging of 30 cycles of the alloy electrode is increased from 576.2 to 597.5 mA· h/g, and the capacity retention rate and high-rate dischargeability (HRD) of the alloy electrode are increased by 20.5% and 29.4% respectively compared with those of the alloy electrode without the La addition, exhibiting the best comprehensive electrochemical performances.