Mechanical Reinforcement and Piezoelectric Properties of PZT Ceramics Embedded with Nano-Crystalline

The double-scale lead zirconate titanate （PZT） piezoelectric ceramics were prepared by the solid state processing with PZT nano-crystalline and micro-powder. The microstructures, electrical and mechanical properties of the double-scale PZT are investigated. All the sintered ceramics exhibit a single perovskite structure and the grain size of the dou ble-scale PZT reduces due to the incorporation of PZT nano-crystalline. Compared to normal PZT, the mechanical properties increase significantly and the piezoelectric properties decrease slightly. Mechanisms responsible for the reinforcement of the double-scale PZT are discussed.     

Dynamic Fracture Toughness and Failure Mechanisms of ZnO Whiskers Secondary Reinforced Composites

Quasi-static and dynamic fracture properties and damage mechanism of glass fiber polymer composites embeaaea with different mass percentages of ZnO whiskers are investigated by using an Instron Testing machine and a Split- Hopkinson pressure bar. According to the experimental results and linear fracture mechanics, the quasi-static fracture toughness Kic and the dynamic fracture toughness Kid under various impact velocities of specimens are obtained. Fracture mechanism is investigated by fractography analysis with a scanning electron microscope. The experimental results show that the mass percentage of ZnOw has little influence on the quasi-static fracture toughness, but a little influence on the dynamic fracture toughness and time of initial fracture point of specimens by the reason of various fracture mechanisms.     

Effect of Interface Nanotexture on Light Extraction of InGaN-Based Green Light Emitting Diodes

We report the enhancement of the light extraction of InGaN-based green light emitting diodes （LEDs） via the interface nanotexturing. The texture consists of high-density nanocraters on the surface of a sapphire substrate with an in situ etching. The width of nanocraters is about 0.5 μm and the depth is around 0.1 μm. It is demonstrated that the LEDs with interface texture exhibit about a 27% improvement in luminance intensity, compared with standard LEDs. High power InGaN-based green LEDs are obtained by using the interface nanotexture. An optical ray-tracing simulation is performed to investigate the effect of interface nanotexture on light extraction.     

基于神经网络的闪光照相网栅图像修补

提出了一种基于径向基函数（RBF）神经网络的闪光照相网栅图像修补算法,该方法采用滑动窗口方法将待修补的网栅图像分为若干子块,然后在每个子图像内分别引入RBF神经网络,将栅孔内图像作为已知数据计算RBF网络参数,并以此对每个子图像进行修补,数值试验表明,该算法能较好地再现图像边缘信息,修复的图像在信噪比和视觉方面都优于线性插值和样条插值的结果。     

First-principles study on the geometric and electronic structures and phase transition of PbZr1-xTixO3 solid solutions

With first-principles virtual-crystal approximation calculations, we systematically investigate the geometric and elec- tronic structures as well as the phase transition of lead zirconate titanate (PbZr1-xTixO3 or PZT) as a function of Ti content for the whole range of 0 ≤ x Ti ≤ 1. It can be found that, with the increase of the Ti content, the PbZr1-xTixO3 solid solu- tions undergo a rhombohedral-to-tetragonal phase transition, which is consistent with the experimental results. In addition, we also show the evolution in geometric and electronic structures of rhombohedral and tetragonal PbZr1-x TixO3 with the increasing content of Ti.     

Simultaneous least squares fitter based on the Lagrange multiplier method

We developed a least squares fitter used for extracting expected physics parameters from the correlated experimental data in high energy physics. This fitter considers the correlations among the observables and handles the nonlinearity using linearization during the χ² minimization. This method can naturally be extended to the analysis with external inputs. By incorporating with Lagrange multipliers, the fitter includes constraints among the measured observables and the parameters of interest. We applied this fitter to the study of the m D⁰-D⁰ mixing parameters as the test-bed based on MC simulation. The test results show that the fitter gives unbiased estimators with correct uncertainties and the approach is credible.     

Stationary Fluid Dynamic Behaviour of V-Shaped Diffuser/Nozzle Elements for Valveless Micropump

A novel type of V-shaped （isosceles triangle cross-section） diffuser/nozzle element is proposed for use for valveless micropump. Stationary fluid dynamic behaviour of V-shaped diffuser/nozzle elements in a valveless micropump is investigated by experiment and simulation. Both the results agree well with each other when the Reynolds number is higher than 100 and the pressure loss coefficient ratio of micropump nearly always keeps a constant. For a single V-shaped diffuser, the general trends of variation of pressure loss coefficient with opening angle and Reynolds number are opposite in small and large angles. Compared with conical and flat-wall diffusers, V-shaped diffuser shows the smallest pressure loss when the Reynolds number is 200.     

22Cr双相不锈钢钝化膜组成及其半导体性能研究

借助于Mott-Schottky方程分析了成膜电位、成膜时间、成膜温度以及氯离子等因素对22Cr双相不锈钢在碳酸氢钠/碳酸钠缓冲溶液中所成钝化膜半导体性能的影响, 同时借助于X射线光电子能谱(XPS)技术分析了所成钝化膜的组成. 结果表明: 22Cr双相不锈钢在碳酸氢钠/碳酸钠缓冲溶液中所成钝化膜呈n-p型半导体结构, 钝化膜内施主/受主密度随成膜电位增加、成膜时间延长、成膜温度降低、以及介质中氯离子浓度的降低而减小, 同时膜对基体保护作用随这些因素变化而增强. 钝化膜的XPS分析表明, 钝化膜呈现双层结构, 外层膜主要由三价铁的氧化物(Fe2O3)组成, 内层膜主要由三价铬氧化物(Cr2O3)以及少量二价铁氧化物(FeO)组成.     

利用非线性光纤环路镜将20Gb/s的OTDM信号变换26nm

本文利用非线性光纤环路镜成功地将中心波长为1533.9nm的20Gb/s(8×2.5Gb/s)的OTDM信号变换到1553.3nm和1560.3nm,变换的最大间距达26nm,测量了变换后信号光的眼图和光谱图,并对实验结果进行了分析。     

超宽带可调谐SOA四波混频波长变换器的实验研究

基于半导体光放大器(SOA)光纤环形激光器中的双泵浦四波混频效应,构成超宽带并且完全透明的波长变换器,成功实现1550nm窗口2.5Gb/s信号的可调谐波长变换,变换效率在50nm范围内保持基本平坦,同时测出了SOA增益和自发辐射(ASE)噪音功率的关系.实验结果表明,在一定限制条件下,提高泵浦功率可以提高变换信号的信噪比.