High Solubility of Hetero-Valence Ion （Cu^2＋） for Reducing Phase Transition and Thermal Expansion of ZrV1.6P0.4O7

Large thermal expansion at room temperature and high phase transition temperature of ZrV2O7 limit its practical applications and are reduced by the high solubility of hetero-valence ion （Cu^2＋） on the basis of an equal-valence substitution of P^5＋ for V^5＋. The temperature-dependent Raman spectra show that Zr0.9CU0.1V1.6P0.4O6.9 maintains a normal parent cubic structure till 173 K and transforms to a 3 × 3 × 3 cubic superstructure below 173K. Temperature dependent x-ray diffraction patterns of Zr0.9CU0.1V1.6P0.4O6.9 show near zero and negative thermal expansion. High solubility of lower valence Cu^2＋ relates to an equal-valence substitution of smaller pH for P^5＋, which extends the bond angle of V（P）-O-V in ZrV1.6P0.4O7 close to 180°. The change of microstructure is considered to be responsible for reduced phase transition temperature and thermal expansion.     

Near-zero thermal expansion in β-CuZnV2O7 in a large temperature range

We report a new type of near-zero thermal expansion material β-CuZnV₂O₇ in a large temperature range from 173 K to 673 K. It belongs to a monoclinic structure (C2/c space group) in the whole temperature range. No structural phase transition is observed at atmospheric pressure based on the x-ray diffraction and Raman experiment. The high-pressure Raman experiment demonstrates that two structural phase transitions exist at 0.94 GPa and 6.53 GPa, respectively. The mechanism of negative thermal expansion in β-CuZnV₂O₇ is interpreted by the variations of the angles between atoms intuitively and the phonon anharmonicity intrinsically resorting to the negative Grüneisen parameter.     

ZrV2-xPxO7固溶体的相变与热膨胀性质的研究

本文采用固相烧结法制备了ZrV2-xPxO7@=0,0．2,0．4,0．6,0．8,1）系列材料．粉末X射线衍射（XRD）分析表明,所制备材料的结构为单一立方相．应用变温拉曼光谱研究该材料相变,变温拉曼光谱研究结果表明,材料起始相变温度随着P5＋替代V5＋量的增加逐渐降低,x=0,0．4,0．8,1对应的相变温度分别为383K,363K,273K,213K．热膨胀测试结果表明：随着P替代量的增加正一负膨胀转变温度先降低后增加,x=0,0．2,0．4,0．6,0．8,1对应的正一负膨胀转变温度分别为429K,403K,372K,390K,398K和435K．本文指出了该系列材料存在两个相变过程,为设计和制备ZrV2O7基室温附近的负热膨胀材料奠定了良好的基础．     

新型LED智能控制卡

本文主要做的是LED显示屏的控制系统。此控制系统取代了传统LED显示屏"计算机+发送卡+接收卡+LED显示屏"的控制模式,无需以前繁杂的布线,直接转变为新型的"嵌入式平台+LED智能控制+LED显示屏",通过计算机控制嵌入式平台,得到我们想要显示的画面。     

基于单片机的脉冲频率测量系统的设计

本文设计了基于单片机脉冲频率测量系统,包括放大整形电路、单片机和显示电路等。该测量系统利用AT89C51单片机控制,通过放大整形电路变成所需要的矩形脉冲波形,可以实现多种波形的频率检测。最后通过Keil进行程序编写,Protutes进行仿真,能够精确地完成波形频率的测量。     

基于神经网络的手写体数字识别

本文重点解决以图像方式存在的手写体数字识别问题,首先对图像进行预处理,其次对结构特征进行提取,最后利用神经网络模型对前面两步得到的样本数据进行学习和训练.通过MATLAB进行仿真,神经稀疏编码算法应用在手写体数字识别中能够得到比较好的识别率.     

基于PC104总线的性能检测系统

为了适应外场装备检测装置的需求,以某型自行火炮的随动系统为例,基于PC104嵌入式控制总线的高效数据传榆特点,采用SCM/LX-3160主板和ADT620、CDT2000数据采集板,完成数据采集与转换的硬件配置.并把处理后数据通过Visual C＋＋软件开发工具进行实时显示,确定随动系统的工作状态.应用结果表明,该性能检测系统携带方便,能实时采集信号,并对信号进行准确的分析处理,具有较高的实时性和稳定性.