Results 41 to 50 of about 8,663 (187)
Zhejiang Daxue xuebao. Lixue ban, 2012 电网不对称故障时，快速、准确地检测同步相位和对称分量是电力电子装置实现控制与保护的关键问题之一.分析了负序分量对传统三相锁相环检测性能的影响，设计了 一种频率自适应的同步相位与瞬时对称分量检测新方法.该方法利用瞬时对称分量理论在两相静止坐标系下实现对称分量的实时检测，利用广义二阶积分器实现90°相移，用测得的基波正序电压q轴分量作为锁相环的输入，用锁相环的输出角频率作为相移电路的谐振角频率，达到谐波抑制与频率自适应跟踪，是一个闭环的实时检测系统.分析了该方法的实现机理，给出了检测电路的实现框图 ...
CHENHai-rong(陈海荣) +2 more
doaj +1 more source
Novel Ensemble Analytic Discrete Framelet Expansion for Machinery Fault Diagnosis [PDF]
, 2014 小波变换被称为“数学显微镜“,它对机械信号的多尺度分析在机械设备状态监测和故障诊断领域发挥着重要的作用。然而传统二进小波变换在工程应用中存在一些显著的不足,如平移敏感性、小波尺度能量泄漏、固定的二进“频率？尺度“划分网格等。尤其是后者使得经典小波变换对处于二进网格过渡带的特征分析中产生不可避免的“盲区“。基于此,提出一种基于过完备小波紧框架的新式“时间-尺度“分析方法-衍生增强离散解析小波分析框架。该小波分析框架基于双树复小波变换进行构造,通过合理地选择双树复小波基函数 ...
何正嘉 +3 more
core +1 more source
Distribution, scale, and drivers of mass mortality events in Europe's freshwater bivalves
Conservation Biology, Volume 40, Issue 2, April 2026.Abstract Mass mortality events (MMEs) are decimating populations and compromising key ecosystem functions around the globe. One taxon particularly vulnerable to MMEs is freshwater bivalve mollusks. This group has important ecosystem engineering capacities and includes highly threatened and highly invasive taxa.
Daniel A. Cossey +39 more
wiley +1 more source
Gaoya dianqi, 2018 文中提出一种基于时频分析的GIS多源局部放电信号脉冲分离方法。首先,对记录的GIS局部放电脉冲波形序列进行S变换时频分析,以提取典型局部放电脉冲的时间—频率—幅值特征。然后,与由单一典型局部放电缺陷模型构造的时频数据库进行混合,基于时频相似度分析和仿射聚类方法对记录的脉冲群进行快速分类,最终实现多局部放电源脉冲群的分离。在局部放电源个数未知的情况下,文中方法可判断出局部放电源的个数和放电类型。且该方法可抑制随机干扰源的影响,并可分离典型的脉冲扰动波形。
高敬贝 +6 more
doaj
Automating the analysis of public saliency and attitudes toward biodiversity from digital media
Conservation Biology, Volume 40, Issue 2, April 2026.Abstract Measuring public attitudes toward wildlife provides crucial insights into human relationships with nature and helps monitor progress toward Global Biodiversity Framework targets. Yet, conducting such assessments at a global scale presents challenges.
Noah Giebink +8 more
wiley +1 more source
Dizhen xuebao, 2021 基于北美沿岸和内陆地震台站的连续地震波形记录，并结合沿岸台站附近布设的DART系统记录的海底压力数据以及预测潮汐数据，利用时频分析和极化分析方法对2011年3月11日日本东北部海域MW9.0大地震所激发的海啸对地震背景噪声所产生的影响予以深入分析。结果显示：海啸对高频噪声（1.3—1.5 Hz）以及短周期双频微地动噪声（0.18—0.4 Hz）的影响较小，但海啸显著增强了长周期双频微地动（0.1—0.15 Hz）、单频微地动（0.05—0.08 Hz）以及地球背景自由振荡（0.004—0.007 Hz ...
Fei Chen, Mei Xue
doaj +1 more source
Multiband FMCW Radar LSS-target Detection Dataset (LSS-FMCWR-1.0) and High-resolution Micromotion Feature Extraction Method [PDF]
Detection of small, slow-moving targets, such as drones using Unmanned Aerial Vehicles (UAVs) poses considerable challenges to radar target detection and recognition technology.
Gang Yu +6 more
core +1 more source
Genomic responses to increased temperature and pollinator selection in Brassica rapa L.
New Phytologist, Volume 250, Issue 2, Page 1231-1247, April 2026.Summary Rapid environmental change reshapes both abiotic stress and biotic interactions, yet it remains unclear how these combined forces structure plants' genomic adaptation. In particular, the joint influence of temperature and pollinator identity, two ecological axes undergoing simultaneous global shifts, has rarely been quantified at genomic ...
Yanqian Ding, Florian P. Schiestl
wiley +1 more source
Gaoya dianqi, 2019 针对单轴传感器在断路器中应用的缺陷与不足,为了获取更多断路器分合闸时的状态信息,利用三维振动传感器同步采集断路器操作时振动信号,在时域、频域方面以及时频联合对X、Y、Z 3个方向的信号进行分析对比。在时域方面,运用X、Y、Z3个方向振动信号各个特征和能量的分布;在频域方面,运用快速傅立叶算法得出频谱分布图和功率谱图;在时频联合方面,运用小波包分解将三维传感器信号进行分解,并求出能量在各节点的分布和Wigner-Ville分布,说明三轴传感器放置方向对断路器测量信号故障诊断正确率的影响。实验分析结果表明 ...
丁巧林 +3 more
doaj
European Policy Analysis, Volume 12, Issue 2, Spring 2026.ABSTRACT This article explains why the European Union Wildfire Risk Management instruments have evolved since the 1980s, even though the underlying patterns of wildfire events have remained largely unchanged. It argues that these changes stem from competing institutional actors promoting distinct policy frames within the European Union's (EU ...
Damien Ballereau, Sabine Saurugger
wiley +1 more source