Torsion sensor based on two cascaded long period fiber gratings fabricated by CO2 laser pulse irradiation and HF etching technique respectively

A novel torsion sensor is proposed, which is composed of one long period fibre grating and one asymmetrically corrugated long period fibre grating based on the high-frequency CO₂ laser pulses technology and burning fibre coating and etching cladding technology, respectively. By combing the advantages of the two aforementioned elements, a sensitivity of 331.7 and 310.3 pm/(rad/m) towards clockwise and anticlockwise direction, respectively, is reached in the experiments.     

CAD在三坐标测量机中的应用

近几年各个三坐标测量软件开发厂商相继在自己的软件中加入了CAD功能,且功能越来越强大。本文就CAD在三坐标测量软件中的使用和其功能作简要阐述。     

尖晶石相型LiM_(0.2)Mn_(1.8)O_4(M=Mg、Cd)相的晶格畸变与红外吸收峰频移

通过室温固相法制备了不同元素掺杂的前驱体,并采用分步煅烧法获得了尖晶石型LiMn2O4和LiM0.2Mn1.8O4(M=Mg、Cd)相。采用XRD和FTIR技术就元素掺杂对产物晶格畸变、Mn—O键长和键能强度等微观结构参数和光谱频移现象进行分析。结果表明,不同元素掺杂导致产物产生不同程度的晶格畸变。Mg元素掺杂使晶格收缩,Mn(Ⅳ)—O和Mn(Ⅲ)—O键收缩和键能强度增加,对应吸收峰发生蓝移;Cd元素掺杂使晶格膨胀,Mn(Ⅳ)—O和Mn(Ⅲ)—O键增长和键能强度降低,对应吸收峰发生红移。     

An efficient second‐order characteristic finite element method for non‐linear aerosol dynamic equations

In the paper we consider the non‐linear aerosol dynamic equation on time and particle size, which contains the advection process of condensation growth and the process of non‐linear coagulation. We develop an efficient second‐order characteristic finite element method for solving the problem. A high accurate characteristic method is proposed to treat the condensation advection while a second‐order extrapolation along the characteristics is proposed to approximate the non‐linear coagulation. The method has second‐order accuracy in time and the optimal‐order accuracy of finite element spaces in particle size, which improves the first‐order accuracy in time of the classical characteristic method. Numerical experiments show the efficient performance of our method for problems of log‐normal distribution aerosols in both the Euler coordinates and the logarithmic coordinates. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of Anti-Oxidant Migration on Friction and Wear of C/C Aircraft Brakes

The surfaces of carbon-carbon (C/C) aircraft brakes are usually coated with anti-oxidant to protect them from oxidation. These surfaces do not include the friction surfaces since it is known that when anti-oxidant get onto the friction surface, the friction coefficient decreases. The anti-oxidant migration (AOM), however, happens during processing, heat treatment and application. In this study, phosphorus based anti-oxidants inhibited 3-D C/C aircraft brake system was investigated. The effects of their migration on friction and wear in the 3-D C/C brakes were revealed by sub-scale dynamometer tests and microscopic analysis. Dynamometer results showed that when AOM occurred, both landing and taxi coefficients decreased in humid environment and the wear was slightly lowered. Microscopic study showed that under high humidity conditions there was no formation of the friction film.     

Antireflection and band gap extension effects of ZnO nanocrystalline films grown on ITO-coated glasses by low temperature process

Zinc oxide (ZnO) nanocrystalline films coated on indium tin oxides (ITO, 90:10 wt%) glasses were prepared by low temperature process. The thin films were composed of uniform nanoparticles with average diameter around 8.4 nm. All samples exhibited excellent optical antireflective phenomena, and the maximum transmission reached 92.8% for the sample spin coated at 1500 rpm at 453 nm, improved by 21.5%. The antireflective results were explained by the coherence theory. And the antireflective effects were induced by the ITO and ZnO films. The calculated thicknesses of the ZnO films agreed well with the experimental results. The theoretical calculated band gap from the average diameter of ZnO nanoparticles was also well consistent with the experimental ones obtained from the optical transmission spectra. This result was promising for applications in organic solar cells.     

往复副螺棱高度对单螺杆挤出机内混合行为的影响

建立了带有扰动副螺棱的单螺杆均化段数学模型,探讨了不同副螺棱高度对混合的影响。将有限体积方法与叠加网格技术相结合,得到了螺槽内牛顿流体三维等温周期性速度场。采用4阶Runge-Kutta方法进行流体前锋追踪计算,得到了粒子群及示踪剂界面混合行为。Poincaré截面揭示了混沌混合在螺槽横截面内呈现"8"字形带状分布,内外分别被准周期运动区域填充。副螺棱高度越大,混沌混合区域所覆盖的尺度越大,混合能力越好。