Sol-gel processed silica/titania/ÿ-Glycidoxypropyltrimethoxysilane composite materials for photonic applications

Silica/titania/?-Glycidoxypropyltrimethoxysilane composite materials processed by the sol-gel technique were studied for photonic applications. Waveguide thin films with thickness more than 1.7 μm were prepared by the sol-gel spin coating technique and low temperature heat treatment from this high titanium content composite materials. The films were analyzed by atomic force microscopy (AFM), ellipsometry, differential thermal analysis (DTA), thermal gravimetric analysis (TGA), UV-visible spectroscopy (UV-VIS), and Fourier transform infrared (FT-IR) spectroscopy. It was observed that the film becomes thinner as the titanium contents increase. A change of the refractive index through the range 1.52–1.61 at the optical wavelength of 633 nm was achieved by varying the molar ratio between silica and titanium. A dense, low absorption, and high transparency in the visible range waveguide films could be obtained at a low temperature. It was also noted that organic compounds in the film would decompose in the temperature range from 200°C to 480°C. Accordingly, purely inorganic silica-titania films with a thickness of about 0.7 μm could also be obtained by a single-coating process, when the film was baked at a temperature of 500°C or higher. The waveguides properties and photonic applications of the composite material solgel films were also investigated.     

WCDMA与GPRS技术浅析

主要介绍了WCDMA技术与GPRS技术的基本概念,并对二者进行了比较,指出在向第三代移动通信系统(3rdGeneration,简称为3G)过渡的时代,这两种技术各有所长,必将有一番大的较量。     

LTE系统中Turbo译码的改进算法

LTE系统对可靠通信提出了更高的要求,这在一定程度上依赖于信道编码的性能。针对LTE系统中的Turbo译码算法进行了研究,在Max-Log-MAP和Log-MAP算法的基础上提出了一种改进算法。理论分析和仿真结果表明,这种改进算法的性能有进一步提升,并且更加易于硬件实现,具有较低的复杂度。     

计算层析成像光谱仪中二元光学元件的研究

报道了用二元光学技术制作的二维位相型衍射光栅作为计算层析成像光谱仪中的光谱元件.对该光谱元件衍射阵列的强度分布、衍射效率以及各衍射级效率对波长的响应曲线进行了实验检测.结果表明,实验与理论相一致.     

Friction modeling and adaptive compensation using a relay feedbackapproach

In this paper, the application of a dual-relay feedback approach toward modeling of frictional effects in servomechanisms is addressed. The friction model consists of Coulomb and viscous friction components, both of which can be automatically extracted from suitably designed relay experiments. At the same time, the dynamical model of the servomechanical system can be obtained from the experiments. Thus, a proportional-integral-derivative feedback motion controller and a feedforward friction compensator can be automatically tuned in this manner. The friction model obtained is also directly applicable to initialization of an adaptive control scheme proposed. Results from simulation and experiments are presented to illustrate the practical appeal of the proposed method     

High quality interpoly dielectrics deposited on thenitrided-polysilicon for nonvolatile memory devices

High quality interpoly dielectrics have been fabricated by using NH₃ and N₂O nitridation on polysilicon and deposition of tetra-ethyl-ortho-silicate (TEOS) oxide with N₂O annealing. The surface roughness of polysilicon is improved and the value of weak bonds is reduced due to nitrogen incorporation at the interface, which improves the integrity of interpoly dielectrics. The improvements include a higher barrier height, breakdown strength, and charge-to-breakdown, and a lower leakage current and charge trapping rate than counterparts. It is found that this method can simultaneously improve both charge-to-breakdown (up to 20 C/cm² ) and electric breakdown field (up to 17 MV/cm)     

矿热炉用熔渣烘炉

本文介绍了矿热炉开新炉时熔渣烘炉过程,烘炉时炉壳温度随时间的变化,并按每个烘炉阶段同传统的方法作了比较,表明这是一种节能烘炉方法。     

提高空冷机组经济性的研究

通过对大同第二发电厂两台２００ＭＷ空冷机组的经济性分析,以及对煤耗影响进行的详细计算,从大同地区的实际气象条件出发,对怎样提高空冷机组的经济性提出了 和分析计算方法,对可能挖潜的降耗措施进行了分析。     

设计余弦调制QMF组的一种新方法

通过适当矩阵变换，本文首先将精确重建余弦调制正交镜像滤波器组的设计转化为一种带约束的非线性优化问题，它是一种带二次型约束的最小二乘（ＱＣＬＳ）优化问题，然后，我们提出了一种变参量的罚函数方法来有效求解该类ＱＣＬＳ优化问题，通过直接采用原型滤波器系数为优化变量，我们构造了一个特殊的凸函数作优化代价函数，故可获得该问题的全局最小点，最后，采用本文提出的设计方法进行了一个具体实例设计，结果表明我们的方法     

脉冲MOS结构少子产生寿命的统一表征

本文提出了一种采用脉冲ＭＯＳ结构测量少子产生寿命的统一表征谱方法，此方法基于任何一种收敛弛豫过程均可以转换成一种衰减的指数函数的思想，应用关以样原理获得脉冲ＭＯＳ结构瞬态电容差值谱，从谱图中我们可以直接得到关于少子产生寿命信息。本文综合了众多脉冲ＭＯＳ结构测量少子产生寿命的物理模型，分析了不同模型之间的精细差别。