Spatial ions distribution of the bonding interface in YAG/Nd:LuAG composite laser ceramic

Composite YAG/Nd:LuAG transparent ceramics were fabricated by a thermal bonding process. The spatial distribution of ions around the original bonding interface of the YAG/Nd:LuAG composite laser ceramic was investigated. Around the original bonding interface, Lu³⁺ and Y³⁺ ions were replaced with each other in dodecahedral symmetry sites. Results from X‐ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) quantitative chemical analyses positively show that the distance of Y³⁺ ions diffused in the LuAG part is about 35 μm, while Lu³⁺ ions’ diffused distance in the YAG part is about 5 μm. This corresponds to the diffusion coefficient of Y³⁺ ions and Lu³⁺ ions (D_Y=2.43 ×10^?10 cm²/s and D_Lu=0.56×10^?10 cm²/s at 1750°C). The formation of Y_xLu_(3?x)Al₅O₁₂ polycrystal in the bonding section explains the complete combination of LuAG and YAG without a bonding interface. Moreover, no diffusion phenomenon of Nd³⁺ ions was detected near the original bonding interface.     

轿车转向节臂振动加载试验与仿真

本文设计了用于转向节臂等零部件进行强度试验的电液伺服加载系统，建立了系统数学模型和传递方块图，再进行系统仿真，得出了加载系统的响应曲线，论证了系统的可行性和可靠性，从而构建一个性能优良的加载装置。     

Reduction of flow-induced noise in a household air purifier

Journal of Mechanical Science and Technology - In this study, we propose a design for a household air purifier that reduces the flow-induced noise caused by the impeller of the fan system. The...     

Cryptanalysis of the new TTS scheme in CHES 2004

We combine the method of searching for an invariant subspace of the unbalanced Oil and Vinegar signature scheme and the Minrank method to defeat the new TTS signature scheme, which was suggested for low-cost smart card applications at CHES 2004. We show that the attack complexity is less than 2⁵⁰.     

Effects of deformation rate on properties of Nd,Y-codoped CaF2 transparent ceramics

Different deformation rates of Nd,Y-codoped CaF₂ transparent ceramics were prepared by ceramization of single crystals. The deformation rate effects on the crystallization behaviors, microstructures, mechanical properties, and optical performances were investigated for the first time. The results indicate that the comprehensive performances of Nd,Y-codoped CaF₂ ceramic (△a?=?62%) are the most optimal compared with other ceramics having different deformation rates (△a?=?34%, 40%, 50%, and 75%). In further investigations of the optical properties, the Nd,Y-codoped CaF₂ ceramic (△a?=?62%) sample exhibited a high transparency (T_a?>?91%, 3-mm thick，250?～?1200?nm), low light scattering, superior fracture toughness (K_1c?～?0.71?MPa·m^1/2), strong fluorescence emission, long lifetime (τ?=?348.72?μs), and broad FWHM (29.2?nm), promising a good candidate for high-power laser material.     

A study on free vibration of a spinning disk

Without a logical jump, we have derived the governing equation for free vibration of a spinning circular disk by using the variational formulation based upon the Kirchhoff plate theory and von Karman strain one. It has been found during the derivation that the governing equation is theoretically valld under the assumption that in plane deflections are steady and axisymmetric, and that internal forces are linearized while the strains remain nonlinear. The natural frequencies and the critical speeds of a freely spinning disk are obtained approximately and their dependencies on the spinning speed, mode number, and natural freqeuncy of the stationary disk are analyzed.     

总结近20年太化氯碱生产的发展

总结了改革开放以来太化在电解产能及技术方面的三次改进。     

加载速率对岩石声发射信号影响的试验研究

加载速率对岩石声发射信号的总体影响是巨大的。通过采集大理岩和红砂岩单轴压缩声发射信号,分析计算了不同加载速率下的声发射过程时间序列的参数,得到了声发射信号与加载速率的变化关系,结果表明,不同加载速率下的声发射信号特征具有明显的不同,随着加载速率的增大,能率和振铃率都随之增大,而产生的能量和振铃计数的总和却逐渐减少小,加载速率的不同,在某种意义上还会影响到岩石的破坏方式,加载速率越大,岩石的破坏越趋于剧烈。     

常用中波红外窗口材料高温透过与热辐射性能比较

在高超音速飞行下,飞行器的中波红外窗口面临着气动加热导致的高温透过率下降和高温辐射增强的挑战,在高马赫应用中,选择窗口材料时必须对材料的高温透过率与高温热辐射这两个性能进行考察.本文采用傅里叶红外光谱仪测试了蓝宝石单晶、钇铝石榴石单晶、镁铝尖晶石陶瓷、氟化镁陶瓷和氧化钇陶瓷5种常见中波红外窗口材料在50℃~400℃的高温透过性能和高温辐射性能.考察了这几种窗口材料的高温透过率下降趋势和高温辐射增强.结果表明,相对于其他3种材料,氟化镁和氧化钇材料在3~5μm应用波段的高温透过率下降很小,同样高温辐射也较小.此外,氧化钇表现出非常优异的超低红外辐射性能,是一种非常有应用前景的中波红外窗口材料.     

Broadening emission band of Yb:LuScO3 transparent ceramics for ultrashort pulse laser

Sesquioxides were considered as promising gain medium for high power ultrafast laser. Broadening of emission spectrum plays a crucial role in shortening the pulse width of laser. In this paper, the ratio of lutetium oxide and scandium oxide was adjusted to control the emission wavelength and spectral width. Highly sinterable Yb:(Lu_xSc_1–x)₂O₃ nanopowders were synthesized through the glycine-nitrate combustion process. Transparent Yb:(Lu_xSc_1–x)₂O₃ ceramics were fabricated via vacuum sintering at 1750℃ for 10 h, among which Yb:(Lu_0.5Sc_0.5)₂O₃ ceramics have the highest transmittance, reaching 78% at 1100 nm. With increasing Lu₂O₃ content, the emission wavelengths corresponding to the two transitions of Yb:(Lu_xSc_1–x)₂O₃ were blueshifted 8 and 15 nm, respectively. Most importantly, from Yb:Sc₂O₃ to Yb:(Lu_0.5Sc_0.5)₂O₃, spectral broadening of the two emission wavelengths was observed by 9 and 16 nm, respectively. Thus, the Yb:(Lu_xSc_1-x)₂O₃ ceramics exhibiting high transmittance and broad emission band are promising for ultrashort pulse generation.