宇航级电连接器空间原子氧效应浅析

低轨道航天器在轨运行期间,外露的电连接器及电缆组件会受到原子氧的剥蚀作用,导致性能衰退,甚至于失效。文章简要地介绍了低地球轨道区域的空间环境,阐述了空间原子氧效应的机制,重点从宇航级电连接器的主要外露零件及其材料选用方面对其空间原子氧效应进行了分析。     

光网络发展展望

光网络的具体含义到底是什么，这是一个仁者见仁，智者见智的问题。但有一点是取得了共识的，即未来的光网络应该是一个应用灵活、可靠、性能稳定的网络。它应该满足传输各种信号，如SDH、ATM、IP等的所有基本要求（即灵活性、可升级性和系统生存性应能独立于比特率和协议）。这样一个网络应该能够对各种信号进行有效的传输、调度、保护和管理。因此，如果我们希望能对光网络今后的发展做一点预测的话，必须综合考虑传输技术、光网络产品、光网络设计以及光标准研究等方面的发展情况，才能尽量避免偏颇。     

Effect of alkyl chain length on the thermophysical properties of pyridinium carboxylates

In the present study,new series of pyridinium carboxylate protic ionic liquids (PILs) were synthesized by pairing pyridinium cation with carboxylate anion from C1-C3 forming pyridinium formate ([CsH6N+][HCOO-]),pyridinium acetate ([CsH6N+][CH3COO-]) and pyridinium propionate ([C5H6N+][CH3CH2COO-]) respectively.The physical properties namely,density,viscosity,surface tension (298.15-343.15) K,and refractive index (293.15-323.15) K were measured.Thermal properties namely,glass transition temperature,molar heat capacity,and thermal decomposition temperatures were also determined.The thermal expansivity was calculated using the experimental density data.The effect of increasing the alkyl chain length on the thermophysical properties of the pyridinium carboxylate PILs has been evaluated.As expected the physical properties i.e.density,viscosity,surface tension and refractive index of the investigated pyridinium carboxylates decreased with increasing temperature.In general pyridinium carboxylate PILs possessed low viscosity,high thermal stability and excellent hydrogen bonding capability,and these properties lead them to outperform conventional solvents employed for lignin dissolution.     

Effect of specimen size on energy dissipation characteristics of red sandstone under high strain rate简

In this experiment, red sandstone specimens, having slenderness ratios of 0.5, 0.7, 0.9 and 1.1 respectively, were subjected to blow tests using a Split Hopkinson Pressure Bar (SHPB) system at a pressure of 0.4 atmospheres. In this paper, we have analyzed the effect of slenderness ratio on the mechanical properties and energy dissipation characteristics of red sandstone under high strain rates. The processes of compaction, elastic deformation and stress softening deformation of specimens contract with an increase in slenderness ratio, whilst the nonlinear deformation process extends correspondingly. In addition, degrees of damage of specimens reduced gradually and the type of destruction showed a transformation trend from stretching failure towards shear failure when the slenderness ratio increased. A model of dynamic damage evolution in red sandstone was established and the parameters of the constitutive model at different ratios of length to diameter were determined. By comparison with the experimental curve, the accuracy of the model, which could reflect the stress–strain dynamic characteristics of red sandstone, was verified. From the view of energy dissipation, an increase in slenderness ratio of a specimen decreased the proportion of energy dissipation and caused a gradual fall in the capability of energy dissipation during the specimen failure process. To some extent, the study indicated the effects of slenderness ratios on the mechanical properties and energy dissipation characteristics of red sandstone under the high strain rate, which provides valuable references to related engineering designs and academic researches.     

三元催化器结构原理与性能评价

介绍了车用三元催化器的结构、工作原理以及常用的性能评价指标，对目前国内外采用的性能评价试验方法也作了介绍。     

STUDY ON A NOVEL ELLIPSOIDAL HELICAL ANTENNA

A novel ellipsoidal helical antenna is proposed and studied in this letter. As a special instance, the hemispherical helical antennas are analyzed firstly, which indicates that the characteristics of a two-arm unit are better than that of a single-arm unit. Based on this, the ellipsoidal helical antenna, formed by changing the axial direction＇s dimension of the two-arm hemispherical helical antenna, is analyzed by the moment method with curved basic and testing function. The effects to VSWR （Voltage Standing Wave Ratio）, gain, polarization and patterns by the axial direction＇s dimensions are investigated. The study results provide dependable gist to the choice of antenna format according to the practical requirements.     

羟基硅酸镁在润滑领域的应用研究进展

针对国内外关于羟基硅酸镁纳米微粒在润滑领域的研究报道进行了详细综述。首先，从羟基硅酸镁的结构特点入手，介绍了其在摩擦学领域的应用，然后列举了羟基硅酸镁纳米微粒的制备方法，总结了化学方法合成羟基硅酸镁纳米微粒过程中的不同反应条件，以及对其形貌调控的影响作用。其次，针对改善羟基硅酸镁在润滑油中的分散稳定性而采用的方法进行了概括。随后讨论了羟基硅酸镁纳米微粒在不同摩擦参数、摩擦对偶以及与稀土元素杂化的摩擦学性能变化规律，分析了其在摩擦副表面的摩擦膜形成机制与作用机理。在已报道的文献基础上，归纳总结了羟基硅酸镁纳米微粒能够产生抗磨减摩性能的潜在润滑机制。最后，提出了未来羟基硅酸镁纳米微粒在润滑领域应用推广所面临的问题与挑战，并针对已有问题给出了相应的解决思路。     

油溶性硼酸镧纳米微粒的制备及其在不同基础油中的摩擦学性能研究

采用表面修饰技术和沉淀法制备油胺修饰的硼酸镧(OAm-LaBO_3)纳米微粒,采用多种仪器设备分析OAm-LaF_3纳米微粒的结构、形貌及化学组成,评价OAm-LaBO_3纳米微粒在矿物油液体石蜡(LP)和合成酯类油癸二酸二异辛酯(DIOS)基础油中的减摩抗磨性能,推测其在LP和DIOS中的摩擦学作用机制。结果表明:OAm-LaBO_3在LP和DIOS基础油中均具有一定的减摩、抗磨性能,其中在LP中减摩性能显著,而在DIOS中抗磨性能突出。主要原因是LP和DIOS的极性不同,OAm-LaBO_3纳米微粒在摩擦过程中分解的有机小分子在摩擦表面吸附的难易程度不同,造成了减摩抗磨机制不同。     

增韧水凝胶的研究进展

水凝胶由交联聚合物网络和大量水组成。与生物组织类似的结构,使得水凝胶广泛应用于人类生活和生物医药领域。但现今水凝胶的进一步应用仍然受限于其较差的力学性能。为此,文中综述了近些年科研工作者们在水凝胶增韧方面的研究进展,并从增韧机理出发,划分为杂交交联、互穿网络、高功能交联剂及其他新型体系,深入分析各种能量耗散机理。此外,还展望了水凝胶未来的增韧机理的发展方向及前景。