Compressive and energy absorption properties of closed-cell magnesium foams

The quasi-static compressive mechanical behavior and deformation mechanism of closed-cell magnesium foams were studied, and the effects of the density of magnesium foams on the compressive and energy absorption properties were also discussed. The results show that the compressive process of closed-cell magnesium foams is characterized by three deformation stages: linear elastic stage, collapsing stage and densification stage. At the linear elastic stage, the peak compressive strength (σ ₀) and Young’s modulus (E ₀) increase as the density increases. Magnesium foams can absorb energy at the collapsing stage. In a certain strain range, the energy absorption capacity also increases as the density of magnesium foams increases.     

Mg2Ni1-xCux (x=0, 0.2, 0.4)合金熔炼法加球磨处理后的储氢性能

采用熔炼法加球磨处理制备Mg2Ni1-xCux(x=0,0.2,0.4)合金。通过XRD和SEM/EDX对合金的相成分和微观组织进行分析。研究表明,3种合金中都有Mg2Ni相形成。随着Cu含量的增加,合金分别形成Mg2Cu相和Cu11Mg10Ni9相。PCT测量结果表明,Cu的添加可以改善合金的吸放氢性能。     

一种反射式光纤传感器的研究

为了解决传统的单端输出Y型分支结构的反射式光纤传感器易受入射光强变化、被测表面形貌不同等因素影响的问题,作者研制了一种具有两个输出端的新结构光纤传感器,并对该光纤传感器在精加工表面上的光反射特性进行了理论分析和实验研究。研究结果表明,光纤测头两输出信号之比与测量距离的变化有较好的线性关系,并能显著减少光源发光强度波动及被测表面粗糙度对位移测量结果的影响,从而有利于提高抗干扰能力和测量精度。因此,这是一种性能比较优越的非接触式微位移传感器。     

TFE/NMP吸收式制冷/热泵的开发研究

分析了以TFE／NMP为新工质的吸收式制冷／热泵系统的组成、循环原理、工质性质,介绍了TFE／NMP吸收式制冷／热泵的开发研究及实验装置等。     

Mechanical properties and energy absorption properties of aluminum foam-filled square tubes

Longitudinal and transverse mechanical properties and energy absorption properties of foam-filled square tubes under quasi-static loading conditions were studied. The foam-filled thin-walled square tube was fabricated with aluminum tube as its shell and closed-cell Al-Mg alloy foam as its core. The results indicated that the plateau region of the load-displacement curve exhibited a marked fluctuant serration which was clearly related to the formation of folds. The longitudinal deforming mode of foam-filled square tube was the same as that of the empty tube, but the fold number of foam-filled square tube was more than that of the empty tube. The longitudinal compression load and energy absorption value of foam-filled square tube were higher than the sum of that of aluminum foam (alone) and empty tube (alone) due to the interaction between tube and filler. In transverse direction, the compression load and energy absorption ability of foam-filled square tubes were significantly lower than those in longitudinal direction.     

退火温度对(Pb_(0.5)Sr_(0.5))TiO_3薄膜光学性能的影响(英文)

以三水醋酸铅、醋酸锶、钛酸丁酯为原料,乙二醇甲醚、去离子水、乙酰丙酮做溶剂。用溶胶-凝胶法制备(Pb0.50Sr0.50)TiO3 (PST)前驱体溶液,通过旋涂工艺在石英玻璃基片上沉积 PST 薄膜。薄膜经 650 至 800 ℃退火 30 min,升温速率为 3℃/min。不同温度晶化的 PST 薄膜用 X 射线衍射测量其晶体结构,用原子力显微镜观测其表面形貌。不同温度退火薄膜的光学透射谱用双光束紫外-可见光分光光度计测量。薄膜的吸收边,即带隙能可以根据直接跃迁估计。650、700、 750 和 800℃退火的薄膜样品的直接带隙能分别为 3.74、3.75、3.76 和 3.75 eV。     

Evaluation of delayed fracture property of outdoor-exposed high strength AISI 4135 steels

Delayed fracture properties of AISI 4135 high strength steels with 1490 and 1310 MPa of tensile strength, represented as B15 and B13, respectively, have been studied by means of slow strain rate test (SSRT) of notched bar specimens after outdoor exposure at rural and coastal areas. The exposed specimens were kept at humid medium before SSRT to reproduce active hydrogen entry influenced by the rust layer and to homogenize hydrogen distribution. The influences of exposure site and exposure time on fracture stress have been investigated. The susceptibility of B15 to delayed fracture was obviously higher than that of B13.     

斜钨矿结构钨酸铅晶体电子结构和光学性质的模拟计算

利用完全势缀加平面波局域密度泛函近似,计算了完整的白钨矿结构和斜钨矿结构的钨酸铅晶体的电子结构,模拟计算了复数折射率、介电函数及吸收光谱。分析了各个吸收光谱的峰值所对应的可能的电子跃迁。计算结果表明:斜钨矿结构的钨酸铅晶体的光学性质与白钨矿结构的钨酸铅存在明显的差异,这说明钨酸铅晶体是一种结构敏感的晶体;计算结果为研究钨酸铅晶体的光学性质与晶体结构之间的关系提供理论基础。     

微穿孔板共振吸声结构在飞机喷流噪音控制上的应用研究

分析了飞机的喷流噪声产生机理,讨论了喷流噪声的控制技术.并将穿孔板共振吸声结构降噪技术应用到飞机的推进系统中,用以降低喷流噪声,并对其实际降噪效果进行了比较分析.     

The Electrical Characterization and NIR Absorption of ITO Film under Different Sputtering Time

Indium-tin-oxide(ITO)films with different sputtering time have been prepared by dc magnetron sputtering method on PET substrate at room temperature.The film structure,thickness,electrical and optical properties are investigated through XRD,SEM,van der Pauw method and FTIR,respectively.The XRD results indicate that all the films are amorphous structure.With the increase of sputtering time,resistivity and transmittance decrease simultaneously.However the absorption gets stronger,especially in near-infrared light region.Through Drude model the plasma frequency is calculated and the calculation result is pretty consistent with films deposited at 60 and 90 min.