基于同杆双回线的双端行波测距方法研究

采用合适的相模变换技术,将同杆双回线解耦成完全独立的模量,然后应用小波变换技术和双端测距原理实现同杆双回线的故障定位,并分析了测距失灵的情况及解决方案。     

配电自动化系统分析及改进方案

配电网是电力网络中直接面向电力用户的一个环节,是检测供电可靠性的重要部分。配电自动化的广泛应用,为调度运行控制能力、故障处理能力和配网检修能力的提高奠定了基础,也对社会保电活动等提供可信的技术手段和技术措施,极大减少停电次数和停电时间。本文结合西咸新区供电公司成立后的配电网规划,对配电网的发展现状、存在的问题进行分析,并从主站信息和馈电线路方面提出了切实有效的改进方案。     

Adaptive switching mean filter using conditional morphological noise detector

The adaptive switching mean (ASM) filter is proposed to remove impulse noise. The filter first identifies the corrupted pixels using conditional morphological noise detection and then removes the detected impulses using the adaptive mean filter. Simulation results indicate that the ASM filter can suppress impulse noise effectively while preserving the details in the image very well, thus providing better restoration performance than many other switching-based filters.     

Polyoxometalate‐Derived Hexagonal Molybdenum Nitrides (MXenes) Supported by Boron,Nitrogen Codoped Carbon Nanotubes for Efficient Electrochemical Hydrogen Evolution from Seawater

MXenes and doped carbon nanotubes (CNTs) have entered into research arenas for high‐rate energy storage and conversion. Herein, a method of postsynthesis of MXenes in boron, nitrogen codoped CNTs (BNCNTs) is reported with their electrocatalytical hydrogen evolution performance. The encapsulation of hexagonal molybdenum nitrate nanoparticles (h‐MoN NPs) into BNCNTs protects h‐MoN NPs from agglomeration and poisoning in the complex environment. In principle, the synergism of B and N dopants on the doped CNTs and confined h‐MoN NPs produces extremely active sites for electrochemical hydrogen evolution. Density functional theory calculations reveal that the active sites for hydrogen evolution originate from the synergistic effect of h‐MoN(001)/CN (graphitic N doping) and h‐MoN(001)/BNC. The h‐MoN@BNCNT electrocatalyst exhibits a small overpotential of 78 mV at 10 mA cm^?2 and Tafel slope of 46 mV per decade, which are dramatically improved over all reported MoN‐based materials and doped CNTs. Additionally, it also exhibits outstanding electrochemical stability in environments with various pH values and seawater media from South China Sea.     

Revealing the Impact of F4‐TCNQ as Additive on Morphology and Performance of High‐Efficiency Nonfullerene Organic Solar Cells

Fluorinated molecule 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) and its derivatives have been used in polymer:fullerene solar cells primarily as a dopant to optimize the electrical properties and device performance. However, the underlying mechanism and generality of how F4‐TCNQ affects device operation and possibly the morphology is poorly understood, particularly for emerging nonfullerene organic solar cells. In this work, the influence of F4‐TCNQ on the blend film morphology and photovoltaic performance of nonfullerene solar cells processed by a single halogen‐free solvent is systematically investigated using a set of morphological and electrical characterizations. In solar cells with a high‐performance polymer:small molecule blend FTAZ:IT‐M, F4‐TCNQ has a negligibly small effect on the molecular packing and surface characteristics, while it clearly affects the electronic properties and mean‐square composition variation of the bulk. In comparison to the control devices with an average power conversion efficiency (PCE) of 11.8%, inclusion of a trace amount of F4‐TCNQ in the active layer has improved device fill factor and current density, which has resulted into a PCE of 12.4%. Further increase in F4‐TCNQ content degrades device performance. This investigation aims at delineating the precise role of F4‐TCNQ in nonfullerene bulk heterojunction films, and thereby establishing a facile approach to fabricate highly optimized nonfullerene solar cells.     

国际电联第二届无线电监测与频谱管理培训培在京举办

5月23日,国际电联第二届无线电监测与频谱管理培训班在国家无线电监测中心北京监测站举行了开学典礼.信息产业部无线电管理局张胜利局长、国家无线电监测中心刘岩主任、国际电联高级顾问Behdad先生出席了开学典礼并讲话.国家无线电监测中心李景春总工程师主持了开学典礼.     

On the Diversity Order of Spatial Multiplexing Systems With Transmit Antenna Selection: A Geometrical Approach

In recent years, the remarkable ability of multiple-input-multiple-output (MIMO) wireless communication systems to provide spatial diversity or multiplexing gains has been clearly demonstrated. For MIMO diversity schemes, it is well known that antenna selection methods that optimize the postprocessing signal-to-noise ratio (SNR) can preserve the diversity order of the original full-size MIMO system. On the other hand, the diversity order achieved by antenna selection in spatial multiplexing systems, especially those exploiting practical coding and decoding schemes, has not thus far been rigorously analyzed. In this paper, a geometrical framework is proposed to theoretically analyze the diversity order achieved by transmit antenna selection for separately encoded spatial multiplexing systems with linear and decision-feedback receivers. When two antennas are selected from the transmitter, the exact achievable diversity order is rigorously derived, which previously only appears as conjectures based on numerical results in the literature. If more than two antennas are selected, we give lower and upper bounds on the achievable diversity order. Furthermore, the same geometrical approach is used to evaluate the diversity-multiplexing tradeoff in spatial multiplexing systems with transmit antenna selection     

氮化硼薄膜的脉冲激光沉积

用Ｑ开关ＹＡＧ激光器的１．０６μｍ的脉冲激光在硅及玻璃衬底上沉积了氮化硼薄膜。做了ＳＥＭ，ＸＲＤ，红外透射谱和紫外一可见透射谱等测试。确认为六方氮化硼（ｈ－ＢＮ）薄膜．并测出其禁带宽度、晶格常数等。     

多跳认知无线Mesh网络中频谱决策与路由的跨层设计

灵活高效的频谱共享技术能够实现频谱资源的最大化利用,有效地缓解了无线频谱紧缺的现状。在一个与TDMA/FDMA蜂窝网络共存的多跳认知无线Mesh网络环境下,基于覆盖式（Underlay）与机会式（Overlay）相结合的频谱共享机制,提出了一种有效的链路层频谱决策与网络层路由的跨层设计方案。仿真结果表明,该方案比基于最小跳数的随机信道选择算法在网络端到端传输性能上有显著的优势。     

一种陶瓷方形扁平封装外观缺陷检测方法

提出一种基于机器视觉的陶瓷方形扁平封装外观缺陷检测方法。对于封装外形尺寸较大而缺陷较细微的情形,将待检片分为多个区域与标准样片进行比对检测。首先通过Foerstner特征点检测法提取标准片图像的特征点,然后使用随机抽样一致性(RANSAC)图像匹配算法,将所有标准片图像拼接并融合生成一张标准片全幅面模板,再将待检片分区与标准片模板进行序贯比对,以提取可疑区域,最后利用支持向量机(SVM)分类器对可疑区域进行筛选分类。实验结果表明,这种方法不仅克服了传统视觉检测过程中视野范围与图像分辨率相互制约的矛盾,且对陶瓷方形扁平封装表面缺陷具有较高的检出率。