有源电力滤波器对不同类型谐波源的补偿特性

研究了电力系统中典型的谐波源。通过探讨串联型和并联型APF的工作原理,分析了它们对不同性质谐波源的补偿特性,并分别进行了仿真和实验研究,确定了它们各自适应的补偿对象。最后得出的结论能为工程应用中选择APF提供理论依据。     

A study of cycling induced degradation mechanisms in Si nanocrystal memory devices

The endurance of Si nanocrystal memory devices under Fowler-Nordheim program and erase (P/E) cycling is investigated. Both threshold voltage (V(th)) and subthreshold swing (SS) degradation are observed when using a high program or erase voltage. The change of SS is found to be proportional to the shift of V(th), indicating that the generation of interface traps plays a dominant role. The charge pumping and the mid-gap voltage methods have been used to analyze endurance degradation both qualitatively and quantitatively. It is concluded that high erase voltage causes severe threshold voltage degradation by generating more interface traps and trapped oxide charges.     

瞬时无功功率与传统功率理论的统一数学描述及物理意义

基于将传统功率理论中有效值、相位差、有功功率和无功功率等概念向瞬时值概念的自然扩展,建立了三相电路瞬时无功功率理论与传统功率理论的统一数学描述,深入分析了二者之间的关系,揭示了瞬时无功功率理论的物理意义。     

The Controllable Synthesis of High-Quality Two-Dimensional Iron Sulfide with Specific Phases

2D Fe-chalcogenides have drawn significant attention due to their unique structural phases and distinct properties in exploring magnetism and superconductivity. However, it remains a significant challenge to synthesize 2D Fe-chalcogenides with specific phases in a controllable manner since Fe-chalcogenides have multiple phases. Herein, a molecular sieve-assisted strategy is reported for synthesizing ultrathin 2D iron sulfide on substrates via the chemical vapor deposition method. Using a molecular sieve and tuning growth temperatures to control the partial pressures of precursor concentrations, hexagonal FeS, tetragonal FeS, and non-stoichiometric Fe₇S₈ nanoflakes can be precisely synthesized. The 2D h-FeS, t-FeS, and Fe₇S₈ have high conductivities of 5.4 × 10⁵ S m⁻¹, 5.8 × 10⁵ S m⁻¹, and 1.9 × 10⁶ S m⁻¹. 2D tetragonal FeS shows a superconducting transition at 4 K. The spin reorientation at ≈30 K on the non-stoichiometric Fe₇S₈ nanoflakes with ferrimagnetism up to room temperature has also been observed. The controllable synthesis of various phases of 2D iron sulfide may provide a route for synthesizing other 2D compounds with various phases.     

Supervision localization of timed discrete-event systems

We study supervisor localization for real-time discrete-event systems (DES) in the Brandin–Wonham framework of timed supervisory control. We view a real-time DES as comprised of asynchronous agents which are coupled through imposed logical and temporal specifications; the essence of supervisor localization is the decomposition of monolithic (global) control action into local control strategies for these individual agents. This study extends our previous work on supervisor localization for untimed DES, in that monolithic timed control action typically includes not only disabling action as in the untimed case, but also “clock preempting” action which enforces prescribed temporal behavior. The latter action is executed by a class of special events, called “forcible” events; accordingly, we localize monolithic preemptive action with respect to these events. We demonstrate the new features of timed supervisor localization with a manufacturing cell case study and discuss a distributed control implementation.     

基于单片机的DeviceNet现场总线从站通信接口的开发

DeviceNet是一种工业现场底层设备互联技术,本文详细介绍了以单片机为平台的Device Net现场总线从站接口的开发,并给出了详细的硬件电路和软件设计流程。     

基于非均匀网格的高效高精度洪涝过程模拟

随着计算机技术的发展,网格划分技术日趋成熟.针对变化环境下洪涝灾害频发以及实际地形范围广泛,且通常存在狭长沟道与广阔泛洪区等问题,本文建立了一套具有层次拓扑关系的结构化非均匀网格划分模型,并与基于GPU加速的高分辨率数值模型相结合模拟地表水流动过程.高质量网格影响着模型计算精度与计算效率,非均匀网格划分技术以地形高程的...     

快速鉴别废杂铝合金

废杂铝种类烦多，较实用的方法是将废杂铝分成纯铝、铝-硅、铝-镁、铝-铜、铝-锌合金等五大类，以提高其利用价值和经济价值。化学点滴法快速鉴别废杂铝，既经济又适用。     

快速鉴别废杂铝合金

废杂铝种类烦多,较实用的方法是将废杂铝分成纯铝、铝-硅、铝-镁、铝-铜、铝-锌合金等五大类,以提高其利用价值和经济价值.化学点滴法快速鉴别废杂铝,既经济又适用.     

开发MIS系统中访问远程数据库问题的分析

该文对ＭＩＳ系统开发过程中经常出现的瓶颈问题进行了分析和探讨，并结合实例，比较了用ｐｏｗｅｒ－Ｂｕｉｌｄｅｒ和Ｄｅｌｐｈｉ作前端开发工具时，访问远程数据库的异同。