电力信号相位差测量方法之探讨

在电力系统中常常需要对两个同频率信号(如工频电压和工频电流)之间的相位关系进行准确的测量。本对“相位—时间”法和“功率比例法”这两种传统的相位差测量方法进行了较为详细的分析,对基于离散付里叶变换的相位测量原理进行了详细的讨论,并给出了实测数据。分析表明,基于离散付里叶变换原理的相位测量方法具有测量精度高、抗干扰能力强、电路设计简单等特点。     

基于1/2周期重构DFT的瞬时谐波电流检测

结合带通滤波器的瞬时谐波检测方法,设计了基于1／2周期重构离散傅里叶变换带通滤波器的谐波检测系统。该带通滤波器在基频处幅值为1,在各次谐波处幅值为0,且在基频处的相频特性过零点。系统通过带通滤波器分离出基波分量,再从原电流中减去基波分量得到谐波分量。计算量小于快速傅里叶变换。理论和仿真表明,系统可检测电路稳态和暂态谐波．且缩短了动态响应时间,改善了滤波器的跟踪性能。     

基于动态故障树与蒙特卡罗仿真的保护系统动态可靠性评估

依据数字继电保护系统的功能和工作特点,提出一种保护系统动态可靠性的定量分析方法,旨在为寻找系统薄弱环节、提高保护设计及运行可靠性提供参考依据。首先,确立保护系统累积失效概率、可用度和基本部件概率重要度指标。其次,建立马尔科夫状态空间与动态故障树相结合的微机保护系统动态可靠性模型,提出基于动态故障树结构函数的蒙特卡罗仿真方法,以进行保护系统可靠性定量评估。最后以算例验证所提方法的有效性,并进行相关分析。结果表明该方法对保护系统可靠性评估、部件影响分析及薄弱环节识别具有参考价值。     

二叠氮季戊二醇二硝酸酯的构象和IR谱的密度泛函理论研究

用ＤＦＴ－Ｂ３ＬＹＰ方法计算了二叠氮季戊二醇二硝酸酯（ＰＤＡＤＮ）处于四种构象下的分子几何构型,电子结构和红外光谱,发现其中以一个硝基取反式,另一个硝基和二个叠氮基取顺式时最稳定。在红外光谱中,硝基和叠氮基的理论计算吸收 频率与实验数值具有良好的一致性。     

Orthorhombic Ti2O3: A Polymorph‐Dependent Narrow‐Bandgap Ferromagnetic Oxide

Magnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long‐wavelength regimes. In this work, the discovery of orthorhombic‐structured Ti₂O₃ films is reported as a unique narrow‐bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well‐known corundum‐structured Ti₂O₃ polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti₂O₃ thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti₂O₃ polymorph is found to be n‐type with a very high electron concentration, while the bulk‐type trigonal‐structured Ti₂O₃ is p‐type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti₂O₃, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti₂O₃, which is confirmed by X‐ray magnetic circular dichroism measurements. Using first‐principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti₂O₃. The room‐temperature ferromagnetism observed in orthorhombic‐structured Ti₂O₃, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases.     

ADC测试中INL与THD之间的关系

随着ADC测试技术的不断发展,码密度直方图技术以及采用正弦波输入的离散傅里叶变换(DFT)频域分析技术已经被广泛应用到ADC的仿真和测试分析中。相对于采用DFT进行频域分析获取ADC的动态性能的复杂性来说,采用码密度直方图的方法能简单地得到微分非线性(DNL)和积分非线性(INL)这两个静态性能指标。文章通过对一个10位ADC的行为级模型的仿真分析,阐述了总谐波失真(THD)与INL之间的内在联系,从而提出了通过对INL的测试来评估ADC的THD性能的方法,对今后ADC电路的测试和评估具有指导意义。     

Tailoring Electron‐Transfer Barriers for Zinc Oxide/C60 Fullerene Interfaces

The interfacial electronic structure between oxide thin films and organic semiconductors remains a key parameter for optimum functionality and performance of next‐generation organic/hybrid electronics. By tailoring defect concentrations in transparent conductive ZnO films, we demonstrate the importance of controlling the electron transfer barrier at the interface with organic acceptor molecules such as C₆₀. A combination of electron spectroscopy, density functional theory computations, and device characterization is used to determine band alignment and electron injection barriers. Extensive experimental and first principles calculations reveal the controllable formation of hybridized interface states and charge transfer between shallow donor defects in the oxide layer and the molecular adsorbate. Importantly, it is shown that removal of shallow donor intragap states causes a larger barrier for electron injection. Thus, hybrid interface states constitute an important gateway for nearly barrier‐free charge carrier injection. These findings open new avenues to understand and tailor interfaces between organic semiconductors and transparent oxides, of critical importance for novel optoelectronic devices and applications in energy‐conversion and sensor technologies.     

全兼容IEEE1149.1的MIPS CPU CORE可测性设计

提出了一种采用软硬件协同工作的方式来实现MIPSCPUC：ORE的可测性设计(DFT)方案。硬件全兼容IEEE1149．1(JTAG)标准，支持单步、断点(6个)，内部关键寄存器的查看，并具有可扩充性；软件采用GUI编程开发，达到可视化DEBUG。本设计对于减少DPU开发的测试成本，提高开发效率，以及CPU测试DFT策略的经验积累，都有着一定的意义。     

恒包络OFDM雷达通信一体化研究

提出一种新的OFDM雷达通信一体化系统模型,通过DFT预编码和交织式子载波映射解决了OFDM信号峰均功率比较高的问题,实现了OFDM信号的包络恒定。同时,给出一体化系统信号处理方案,在通信接收端,通过传统的OFDM信号解调得到通信数据。在雷达接收端,通过二维联合搜索和时域相位测量进行目标速度的估计;结合相关处理和频域相位测量,实现雷达的高精度测距。仿真结果表明,在保证通信传输功能的前提下,一体化系统能够实现厘米级别的测距精度和米每秒级别的测速精度。     

一个基于扫描方法的DFT设计与实现

DFT技术已经成为集成电路设计的一个重要组成部分.详细介绍了基于扫描测试的DFT原理和实现步骤,并对一个32位FIFO存储器电路实例进行扫描设计.根据扫描链的特点和电路多时钟域问题,采用了三种设计方案,整个流程包括了行为级Verilog代码的修改、扫描设计综合以及自动测试模板产生(ATPG).对不同的设计方案给出了相应的故障覆盖率,并对生成的模板进行压缩优化,减少了测试仿真时间.最后分析了导致故障覆盖率不同的一些因素和设计中的综合考虑.