航空导管弯曲试验的疲劳裂纹萌生寿命

飞行器液压导管受接头和卡箍等约束，在使用的振动环境中，会因弯曲应力而导致破裂，影响到飞行安全．本文对飞行器液压系统通用的不锈钢导管的裂纹萌生寿命进行了试验研究．首先在对8 mm、12 mm 无缺陷导管和含U 型缺口8 mm 导管的疲劳试验和有限元分析的基础上，得到了导管的最大拉应变-裂纹萌生寿命数据．然后采用基于强度极限和弹性模量估算法的Manson-Coffin 公式来预测导管裂纹萌生寿命．最后引入加载类型修正系数、表面质量修正系数、试样尺寸修正系数、应力集中敏感系数和有效应力集中系数，使修正后的公式对三种类型的导管均有较好的裂纹萌生寿命预测精度．     

Surface Modification of Cu-SSZ-13 with CeO2 to Improve the Catalytic Performance for the Selective Catalytic Reduction of NO with NH3

Kinetics and Catalysis - A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13...     

Multi-stable quantum droplets in optical lattices

Nonlinear Dynamics - We address the nonlinear dynamics of binary Bose-Einstein condensates with mutually symmetric spinor components trapped in an optical lattice. The interaction between the...     

o-Trityl phenoxy-imino vanadium (III) complexes: synthesis,characterization, and catalysis on ethylene (co)polymerization

Several phenoxy-imine ligands bearing o-trityl group in phenoxy moiety RN=CHArOH (Ar = C₆H₂(CPh₃)^tBu, R = 2,6-Me₂C₆H₃ ( L ₁ H ); 2,6-ⁱPr₂C₆H₃ ( L ₂ H ); 3,5-(CF₃)₂C₆H₃ ( L ₃ H ); 3,5-(OMe)₂C₆H₃ ( L ₄ H ); CHPh₂ ( L ₅ H ); CPh₃ ( L ₆ H )) were synthesized and characterized by¹H NMR and ¹³C NMR spectroscopy. The vanadium complexes based on these ligands LVCl₂(THF)₂ ( 1–6 ) were synthesized via conventional transmetalation reaction in moderate to high yields. Complexes 1–6 were fully characterized by FT-IR, elemental analyses and the molecular structures of 1 , 2 ·H₂O, (2 ·H₂O ) ₂ (μ-Cl) ₂ , 4 , and 5 were confirmed by X-ray crystallographic analysis in which the six-coordinated vanadium centers are in a typical octahedral geometry. Upon activation with Et₂AlCl in toluene, complexes 1–6 showed high activities in ethylene polymerization affording polymers with moderate molecular weight (5.9–11.8 × 10⁴ Da). Moreover, in hexane or CH₂Cl₂, 1–6 /Et₂AlCl exhibited enhanced activities. When activated with MAO or MMAO in toluene, these complexes showed relatively low activities but afforded polymers with ultra-high molecular weight (up to 3.30 × 10⁶ Da). 1–6 /Et₂AlCl also showed high activities in ethylene/1-hexene copolymerization at room temperature giving moderate molecular-weight polymers (6.5–11.4 × 10⁴ Da) with co-monomer incorporation being of 6.0 ~ 7.8%.