Results 41 to 50 of about 21,249 (196)
Gaoya dianqi, 2009 受变压器内部复杂结构的影响,局部放电超高频信号在变压器内部的传播特性非常复杂。笔者通过变压器局部放电超高频实验研究,分析了油纸屏障对变压器局部放电被测超高频信号的影响。设计了油中气隙放电、油中沿面放电和油中电晕放电3种局部放电模型,在实验油箱中进行局部放电实验,采用超高频小环天线进行放电信号检测,在有无油纸屏障情况下获得了局部放电超高频信号实测数据,对所测局部放电超高频信号在时域和频域上进行了对比分析。结果表明,油纸屏障对超高频信号幅值衰减及信号功率谱有一定影响。
高红武 +4 more
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Automating the analysis of public saliency and attitudes toward biodiversity from digital media
Conservation Biology, EarlyView.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
Gaoya dianqi, 2018 基于高频法检测局部放电技术已经相对成熟,为了现场检测和对变压器运行状况做出准确诊断,文中提出了利用高频法检测分析放电信号传播特性的方法。通过建立仿真模型确定了频带选择范围,并建立试验平台,利用多传感器同时测量和采集实时信号,对比研究了局部放电在变压器内部传播后以及在不同位置放电时高频信号的频谱特性。结果表明,高频局部放电检测法能够对变压器缺陷进行高效检测且高频信号变化规律明显,为实际的波形检测提供了试验依据。
王新, 苏欢欢, 高树国, 张鹏
doaj
Olhar para o outro tal e qual como ele é, é respeitá-lo na sua integridade
, 2023 Num mundo em constante evolução onde todos temos a capacidade de aprender, a Escola deve ser um lugar seguro para todos. A presente investigação decorreu no âmbito da Prática de Ensino Supervisionada integrada no Mestrado em Educação Pré-Escolar e Ensino no 1º Ciclo do Ensino Básico, tendo como objetivo principal educar para a diversidade presente ...
openaire +1 more source
Simulation and Analysis of the Dynamic Range of the Lunar Radar and A New Algorithm for Surface Medium Electromagnetic Parameters Inversion [PDF]
, 2016 探地雷达(GPR)通过向地下发射高频率宽带电磁波来探测地下物体、地层界面以及地下介质属性和分布结构，被广泛应用于经济建设和军事各领域。由于雷达信号会受到各种电磁和背景噪声干扰，使得接收到的信号不能直接准确地反映地下介质信息，造成对目标检测和识别的困难。特别当处于非理想环境条件下，非目标介质反射信号干扰复杂，目标的反射波很难被识别。在对路面、隧道以及地下等检测时，遇到的地下介质多是层状分布的。人们不仅希望获得各层的深度和厚度，还希望得到各层介质的介电常数和电导率等参数。因此，本文将地表层介质作为研究的对象，
俞子伟
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International Journal of Applied Linguistics, EarlyView.ABSTRACT Previous research has established the relationships between motivation, anxiety, teachers’ support, and self‐regulated learning (SRL) in English‐as‐a‐foreign‐language (EFL) learning. Most of the studies, however, have taken a variable‐centered approach in addressing the variable correlations, while learners’ characteristics and variable links ...
Yuhong Jiao, Barry Bai, Jing Li
wiley +1 more source
AC-AC Converter With High Frequency Link [PDF]
, 2015 电力电子变换技术在过去六十年里已经取得较大发展，人们在AC/DC、DC/DC、DC/AC等领域内的中、小功率变换器研究已经取得了显著成就。然而，对AC/AC变换器研究仅局限于可控硅变换器、矩阵变换器和交流斩波器等交流电网与负载无电气隔离领域。目前国内外对于AC/AC变换技术的研究仍处于初级阶段，寻找一种结构简洁、控制模式方便的主拓扑具有很重要应用意义。 本文通过了解各种典型和新兴的交流变换器主拓扑结构及其性能特点，对高频连接型全桥桥式变换器的电路拓扑、控制原理等进行了深入研究，设计出一款可运行恒压 ...
张少煌
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Attainment Pairing Effects on Cognitive Conflict in Technology‐enhanced EFL Cooperative Tasks
International Journal of Applied Linguistics, EarlyView.ABSTRACT This study examines how attainment pairing (high‐high versus high‐low versus low‐low attainment) impacts English as a Foreign Language (EFL) learner engagement during technology‐enhanced cooperative writing tasks. Seventy‐eight Chinese university learners formed 39 dyads (13 pairs per group) via Tencent Meeting.
Ying Liu, Allen Thurston
wiley +1 more source
滴灌频率和施氮量对温室西葫芦土壤水分、硝态氮分布及产量的影响
Shuitu Baochi Xuebao, 2018 2016年和2017年在北方寒旱地区日光温室西葫芦栽培中，灌溉定额为269.87 mm，设置2个滴灌频率（低频W1：7天1次，高频W2：2天1次）和2个氮素水平（适氮N1：375 kg/hm2，高氮N2：565 kg/hm2），研究不同处理对温室西葫芦土壤水分、硝态氮分布及西葫芦产量的影响。结果表明：（1）高频（W2）滴灌提高了0—40 cm土层的土壤水分，减少了水分的深层下渗。（2）高氮（N2）施肥各土层硝态氮含量较高，适氮处理配合高频次滴灌根区0—40 cm硝态氮含量维持在相对适宜水平，40—80 ...
郭鹏飞 +4 more
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Technology development in nano-sized photocatalyst powder preparation technologies [PDF]
, 2006 Nano-sized semiconductor powders for use as photocatalysts have great potential in environmental and energy engineering applications. The photocatalytic activity of photocatalyst is significantly affected by preparation process since the crystalline ...
Leung, DYC, Leung, MKH, Ni, M
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