高速铣削加工技术在汽车模具制造中的应用

五轴联动铣削可以优化切削过程，参数，有利于降低刀具磨损，减少后加工，是汽车模具加工技术发展的潮流。它适合于使用球头铣刀加工小曲率的凸表面和较浅的凹表面，也可用于使用铣刀侧面加工自由表面。采用3 2轴加工方式下可以最大限度加快走刀。数控铣削比仿型铣削精度高，后加工少。实现五轴高速铣削加工需要不断加强机床计算机数控系统的功能，使之能够直接接收全部设计数据并加以利用，能够有前瞻处理多个程序块，能够方便用户介入计算机辅助制造过程修正设计数据。     

板料激光曲线弯曲成形温度场的数值研究

板料激光弯曲成形是一种利用激光成形构件的柔性成形技术。以矩形板激光单次扫描成形的过程为研究对象，通过对有限元分析软件ANSYS进行二次开发，建立了基于扫描路径的动热源模型，并系统研究了各技术参数下激光弯曲温度场的动态变化。分析发现：（1）曲线扫描准稳态过程的温度峰值要小于同工况下直线扫描情况，且持续时间短暂，温度峰值不断跳跃；（2）相同工艺参数下，随着扫描路径曲率的增大，温度峰值及加热区温度梯度均减小，当扫描路径曲率继续增大时，温度峰值及加热区温度梯度却随之增大；（3）提高激光功率，降低扫描速度以及在恒定线能量密度下增大扫描速度，均使板料温度梯度增大，而增大光斑直径，温度梯度减小。     

An assessment of k-ε turbulence models for gas distribution analysis

This paper presents the gas distribution analysis by injecting air fountain into the containment and simulations with the HYDRAGON code. Turbulence models of standard k-ε(SKE), re-normalization group k-ε(RNG) and a realizable k-ε(RLZ) are used to assess the effects on the gas distribution analysis during a severe accident in a nuclear power plant. By comparing with experimental data,the simulation results of the RNG and SKE turbulence models agree well with the experimental data on the prediction of dimensionless density distributions. The results illustrate that the turbulence model choice had a small effect on the simulation results, particularly the region near to the air fountain source.     

高温石墨炉法测定痕量金属的条件选择

高温石墨炉法测定痕量金属对工作条件的要求非常严格,影响分析准确度和精密度的原因较多。从干燥温度和时间,灰化温度和时间,原子化温度和时间,高温除残温度和时间的选择,自动进样器的调整,试样处理等几个方面,合理、正确地选择工作条件能够得到最佳吸收灵敏度和测量精密度。     

太原南站将建成我国中西部重要交通枢纽

太原南站,一座在建的太原市标志性建筑。建成投入使用的太原南站,还将成为我国中西部的重要交通枢纽,并大幅提升太原市在全国铁路交通的地位以及城市的辐射力和凝聚力。太原南站作为山西第一座大型现代化火车站,对接了石太客运专线、大西客运专线以及太中银等线路,在我国中西部的枢纽作用十分重要。2012年10月初,太原南站站场内,主体建筑和内装修施工基本完工,铁路线引入线工程也已基本完成,站场钢结构雨棚吊装只剩东南一角尚在施工。在这里两台汽车起重机和一台履带起重机,正     

Solid state reaction synthesis and photoluminescence properties of Dy3+ doped NaGd(MoO4)2 phosphor

Dy³⁺ doped NaGd(MoO₄)₂ phosphors were synthesized by a traditional solid-state reaction route using NH₄HF₂ as a flux. The influence of calcination temperature on the crystal structure and spectral properties was studied, and the optimum calcination temperature for producing Dy³⁺ doped NaGd(MoO₄)₂ phosphor was experimentally confirmed. The concentration quenching of Dy³⁺ fluorescence and excitation-wavelength dependent spectroscopic properties were studied. On the base of both the Van Uitert's and I-H models, the electric dipole–dipole (D–D) interaction was ascribed to be the main physical mechanism responsible for energy transfer between Dy³⁺ ions. It was also discovered that the color coordinates of the Dy³⁺ doped NaGd(MoO₄)₂ phosphor depends on the Dy³⁺ doping concentration and the excitation wavelength.     

WC nano-particle surface injection via laser shock peening onto 5A06 aluminum alloy

A novel technique, named nano-particle surface injection via laser shock peening-NPSI/LSP, for surface modification of light alloys is reported. The WC nano-particles were implanted into a 5A06 aluminum alloy surface under a very high pressure (up to Giga or even tens of Giga Pascal), produced by a Q-switched pulsed Nd:Glass laser system. The results confirmed that the surface performance of the 5A06 aluminum alloy have been dramatically improved by the NPSI/LSP process based on an integrated strengthening mechanism of laser shock peening, nano-particles and nano-particle intensified shock peening.     

纳米CeO2在聚合物中的应用

综述了纳米CeO2在提高聚合物的抗老化性能、力学性能、热稳定性能、导电性能及纳米CeO2/聚合物复合材料作为催化材料方面的应用。