基矛电磁波的低流速测量中干扰因素分析研究

介绍了电磁渡测量流速的基本原理一多普勒效应．分析了影响低流速测量的主要干扰因素一发射泄漏干扰和旁瓣干扰。根据接收信号中发射泄漏干扰不变的特性,提出了去均值滤波的方法来消除干扰,对数据进行预处理;根据旁瓣干扰的信号特性,提出了通过频谱加窗和二次加权平均法构造频域带通滤波器来抑制干扰的方法,在仿真比较完各个窗函数的性能之后...     

退火温度对高介电常数Ta2O5薄膜电学性能的影响

利用磁控溅射法在硅(Si)衬底上沉积了Ta2O5薄膜,对薄膜进行了不同温度的退火处理,并利用X射线衍射仪对薄膜的微观结构进行了分析.然后在Si的背面和介电薄膜的上面沉积Pt电极,组成了金属—氧化物—半导体( MOS)电容器,对不同温度下退火得到的薄膜制备的MOS电容器的电学性能进行了研究.结果表明,薄膜在700℃开始结...     

Simultaneously Tuning Band Structure and Oxygen Reduction Pathway toward High-Efficient Photocatalytic Hydrogen Peroxide Production Using Cyano-Rich Graphitic Carbon Nitride

The demands for green production of hydrogen peroxide have triggered extensive studies in the photocatalytic synthesis, but most photocatalysts suffer from rapid charge recombination and poor 2e⁻ oxygen reduction reaction (ORR) selectivity. Here, a novel composite photocatalyst of cyano-rich graphitic carbon nitride g-C₃N₄ is fabricated in a facile manner by sodium chloride-assisted calcination on dicyandiamide. The obtained photocatalysts exhibit superior activity (7.01 mm  h⁻¹ under λ  ≥  420 nm, 16.05 mm  h⁻¹ under simulated sun conditions) for H₂O₂ production and 93% selectivity for 2e⁻ ORR, much higher than that of the state-of-the-art photocatalyst. The porous g-C₃N₄ with Na dopants and cyano groups simultaneously optimize two limiting steps of the photocatalytic 2e⁻ ORR: photoactivity, and selectivity. The cyano groups can adjust the band structure of g-C₃N₄ to achieve high activity. They also serve as oxygen adsorption sites, in which local charge polarization facilitates O₂ adsorption and protonation. With the aid of Na⁺, the O₂ is reduced to produce more superoxide radicals as the intermediate products for H₂O₂ synthesis. This work provides a facile approach to simultaneously tune photocatalytic activity and 2e⁻ ORR selectivity for boosting H₂O₂ production, and then paves the way for the practical application of g-C₃N₄ in environmental remediation and energy supply.     

基于脉冲漏磁的管道腐蚀缺陷检测的研究

输油管道运输中存在着管道腐蚀现象,对管道的安全运行构成威胁.因为常规漏磁检测技术具有一定的局限性,检测近表面和表面下缺陷较难.提出了利用脉冲漏磁的方法检测管道腐蚀缺陷,并对不同深度的缺陷管道进行了实验.结果表明,此方法能有效识别管道表面和表面下腐蚀缺陷,具有快速、定量检测的特点,有广阔的应用前景.     

单晶硅中氢与辐照缺陷的相互作用

对NTD氢区熔单晶硅进行了不同温度下等时退火,采用Hall电学方法测量了电阻率、迁移率随退火温度的变化规律.利用红外吸收技术测量了单晶硅氢区熔退火前后及NTD氢区熔单晶硅不同退火温度下与氢、辐照缺陷有关的红外振动吸收峰变化,对辐照缺陷的退火行为进行了探讨.实验证实NTD氢区熔单晶硅在150～650℃范围内等时退火具有显著特点:在500℃下退火,出现电阻率极小值,即出现浓度很高的过量浅施主;P型向N型转变温度为400℃,迁移率恢复温度为500℃,载流子恢复温度为600℃,均明显低于NTD氩区熔单晶硅转型温度及迁移率和载流子恢复温度,这与氢积极参与辐照缺陷相互作用直接相关.     

激光晶体Nd:YVO4的形貌及生长缺陷

本文报道了应用环境扫描电镜（ESEM）和同步辐射X射线白光形貌术对采用提拉法生长出的Nd:YVO4晶体进行的形貌及生长缺陷的分析,获得了该晶体的开裂表面的ESEM形貌像以及取自晶体肩部和中间部位的（001）面的同步辐射白光形貌像,观察到了位错、包裹物等缺陷,可为生长高质量的Nd:YVO4晶体提供重要的启示.     

Thermodynamic modeling of native point defects and dopants of GaN semiconductors

A thermodynamic modeling of GaN was carried out to describe the thermodynamic behavior of native defects, dopants, and carriers (free electrons and holes) in GaN semiconductors. The compound energy model (CEM) was used. An unintentionally doped GaN was taken as an example. Oxygen was introduced into the model as the unintentionally doped impurity, according to the practical experimental phenomena. The energies of component compounds in the model were defined based on the results of the ab initio calculations and adjusted to fit experimental data. The thermodynamic properties of the defects and the oxygen doped were calculated to show the facility of the model.     

与计算机连接的医疗设备安全问题

阐述了医用电气设备与计算机及其类似设备连接使用的方式.医用电气设备与计算机这两个设备本身检测标准不同,对漏电流的要求也不相同,在利用医用设备进行治疗时,计算机所产生的漏电流存在严重的安全隐患.针对这种情况展开分析,以期企业在生产类似医疗设备时能引起足够的重视,消除隐患.     

深亚微米nMOSFET器件的总剂量电离辐射效应

选取了采用0.25μm工艺的两组器件进行研究.通过对这两种器件关态泄漏电流、跨导和栅电流等电学参数进行分析,得出当器件发展到深亚微米阶段时,影响其辐射效应的主要原因是场氧化层中的陷阱电荷.并对相关机理进行了分析和仿真验证.     

VSF:CMOS组合电路的静态功耗评估模型

为了解决利用晶体管级电路模拟分析CMOS电路静态功耗时模拟时间随电路规模增大迅速增加的问题,在分析晶体管堆叠效应对标准单元泄漏电流影响的基础上,定义了归一化堆叠系数和电路等效堆叠系数的概念,提出了基于电路有效堆叠系数的静态功耗评估模型.该模型可用于CMOS组合电路静态功耗估算和优化.实验结果表明使用该模型进行静态功耗估算时,不需要进行Hspice模拟.针对ISCAS85基准电路的静态功耗优化结果表明,利用该模型能够取得令人满意的静态功耗优化效果,优化速度大大提高.