Fabrication and characterization of 11-kV normally off 4H-SiC trenched-and-implanted vertical junction FET

This letter reports the first demonstration of 101 kV trenched-and-implanted normally off 4H-SiC vertical junction field-effect transistor (TI-VJFET) with a 120 /spl mu/m /spl sim/4.9/spl times/10/sup 14/ cm/sup -3/-doped drift layer. Blocking voltages (V/sub B/) of 10 kV to 11 kV have been measured. The best specific on-resistance (R/sub SP/_/sub ON/) normalized to source active area has been determined to be 130 m/spl Omega//spl middot/cm/sup 2/. Three-dimensional computer modeling including current spreading effect shows that the TI-VJFET would have a specific resistance of 168 m/spl Omega//spl middot/cm/sup 2/ if it is scaled up substantially in size.     

Cohesive crack modeling of influence of sudden changes in loading rate on concrete fracture

The results of an experimental study of a sudden change in loading rate on the fracture behavior of normal- and high-strength concrete specimens of three different sizes are reported. Geometrically similar three-point bend specimens were subjected to either a sudden 1000-fold increase or a 10-fold decrease of the loading rate. It was observed that for a large increase of the loading rate, the post-peak softening can be reversed to hardening followed by a second peak of the stress-strain diagram. A sudden decrease of the loading rate initially causes, a steeper softening slope of this diagram. The results are similar for normal and high strength concrete specimens. The viscoelastic cohesive crack model with the rate-dependent softening law is used to model the experimental results.     

An environmentally friendly coating for corrosion protection of aluminum and copper in sodium chloride solutions

Triacetoxyvinylsilane (TAVS) has been used as precursor to prepare sol-gel under aqueous conditions for the surface treatment of aluminum and copper metals. The corrosion behavior of the sol-gel-treated metals has been investigated with cyclic voltammetry, potentiodyamic polarization and electrochemical impedance spectroscopy. Results from the electrochemical measurements have shown that the TAVS sol-gel-coated metal provided a better corrosion protection than the triethoxysilane (TES) sol-gel-coated metal due to the hydrophobic nature of vinyl group. Contact angle measurements have been conducted and the results have been applied to explain the degree of the corrosion protection of the coating film.     

文象岩中游离石英的测定

本文研究了用磷酸溶矿分析测试文象岩中游离石英的实验原理和方法，并对其准确性进行了验证。结果表明该法简便、快速，有良好的准确度和精密度。完全适用于工业生产测试的要求。     

GPS／Galileo双模捕获引擎的VLSI实现

随着卫星导航进入多星座时代,兼容GPS和Galileo的双模接收机成为目前卫星导航接收机设计的热点。捕获是卫星导航接收机基带信号处理的关键部分之一。本文通过对两种信号捕获算法的分析,提出了一种可以兼容GPS和Galileo信号的捕获引擎的VLSI结构。该结构兼顾了GPS和Galileo的信号特点,可以对GPS信号进行时域并行搜索和对Galileo信号进行时域部分并行搜索。最后给出了该结构各个组成单元的设计方法,在Altera公司的EP2S180FPGA器件上验证通过,并在0．18μm的CMOS工艺下综合,电路规模是3514231平方微米。     

华东电力市场购电策略评估方法

基于华东市场规则和月度购电模拟运行实践,建立起一套完整的购电策略评价体系。提出了购电地位、购电策略和购电效果3类指标,通过对购电前、中、后不同经济行为和技术指标的分析计算,为省（直辖市）电力公司建立合理有效的购电策略提供指导。结合华东市场实际,分析了电网约束对购电策略的影响及评估方法。     

面向润滑站加注系统的CAN通信接口设计

针对目前油田润滑站系统中加注过程繁琐、实时性差等问题,设计了一套由PC机与多台射频读卡控制器组成的润滑站加注系统。介绍了以通用型单片机AT89C52为核心．通过CAN协议控制器和CAN驱动器实现通信接口的设计,给出了硬件原理图及软件流程图。通过CAN通信模块在射频读卡控制器中的应用,有效保证了加注系统中数据通信的实时性、可靠性和稳定性。     

广域环境下基于Q型因子学习方法的电网节点聚合规律?

大规模可再生能源的并网以及电力市场解除管制的改革,使传统集中式的节点电压在线安全分析、调度与控制方法面临困境。对此,在电网运行状况全景过程化可观测条件下,提出了渐进学习的电网节点聚合的新调控理论,通过电网"局部自治与集中调控互融"的调控方式解决电网的调控问题。提出了基于Q型因子学习的电网节点聚合规律的挖掘方法,根据传统节点电压方程及发电机、负荷的等值模型得到广域环境下节点电压向量与电势之间的解析关系,推导出连续2个量测时刻下节点电压幅值变化的影响因子,并对其进行过程化的Q型因子学习,进而得到电压幅值具有一致变化的节点聚合规律。通过对德州电网的仿真分析,验证了所提方法的准确性及有效性。     

基于样本熵的电网电压稳定性能分析

为了分析电网中电压稳定的薄弱节点,提出一种基于幅值序列波动强度和样本熵的电压稳定性能分析方法。首先通过电力系统仿真软件得到电网电压波动的幅值信息,然后依据各负荷节点电压幅值波动序列的波动强度数值,选取进行电压稳定性能分析的最佳序列长度,在此基础上利用动力学中的平坦因子理论提取了每个时段的电压幅值平坦因子,由此构造了一种利用样本熵理论确定电网中电压薄弱节点的方法。最后以某年山东电网冬季运行方式潮流数据为断面,利用传统电压分析理论(如戴维南等值法、连续潮流法)验证所提方法的有效性,为电网的运行与规划提供有益参考。     

多应力条件下可靠性试验数据采集与处理系统的设计

介绍了一种多应力条件下的可靠性试验数据采集与处理系统。系统硬件平台以工控机为基础,从通用雷达板级可靠性试验所涉及测试信号的性质及数据采集的实际要求出发,选用基于PXI总线的数据采集和输出板卡来完成激励信号的加载和响应信号的采集。系统软件采用Labwindow/CVI与VisualC＋＋编程实现,通过调用PXI板卡的驱动函数,实现对板卡的控制以及数据处理;该数据采集系统测试效率、精度高,而且操作简单,具有良好的扩展性。