Results 11 to 20 of about 997,974 (152)
全球能源互联网, 2022 针对模块化多电平换流器型柔性直流输电（modular multilevel converter based high voltage direct current,MMCHVDC）系统中频发的高频谐振现象，提出将矢量电流控制（vector current control,VCC）切换为功率同步控制（power synchronization control,PSC）以抑制其高频谐振的控制策略。首先分析了矢量电流控制下MMC产生高频谐振的机理，并实现了高频谐振现象下由矢量控制到功率同步控制的切换。然后 ...
游广增, 刘鸿超, 芮智, 严正
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Xibei Gongye Daxue Xuebao, 2022 针对高频方波注入法零低速下永磁同步电机无位置传感器控制存在的高频转矩脉动问题, 提出了一种基于双高频方波注入法的双绕组永磁同步电机无位置传感器控制策略。建立永磁同步电机高频数学模型, 分析得到转矩脉动与注入信号的解析关系。对于同相位表贴式双绕组永磁同步电机, 当第一套绕组注入高频方波时, 依据2套绕组的位置关系, 推导了第二套绕组应当注入方波信号的形式, 使同一时刻产生的高频转矩脉动代数和为零, 以消除高频转矩脉动。提取2套绕组高频信号中包含的转子位置估计误差, 比较得到同一时刻误差最小值 ...
ZHOU Qixun +4 more
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Journal of Microbiology and Biotechnology, 2019 β-Glucosidases and β-xylosidases are two categories of enzymes that could cleave out nonreducing, terminal β-D-glucosyl and β-D-xylosyl residues with release of D-glucose and Dxylose, respectively. In this paper, two functional β-glucosidase Dth3 and β-xylosidase Xln-DT from Dictyoglomus thermophilum were heterologously expressed in E.coli BL21 (DE3 ...
Qi, Li +5 more
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Kongjian kexue xuebao, 2023 月球上可能存在大量可用于抗辐射、躲避陨石撞击和月球表面极端温度变化的熔岩管。月球表面杂波识别以及与熔岩管目标回波的区分是月球熔岩管目标探测的重要问题。根据高频电磁波与低频电磁波在月壤中的路径衰减快慢不同，熔岩管道高低频功率比与月表杂波高低频功率比不同的特征，提出了一种利用高低频电磁波功率比进行月表杂波识别的方法。基于分辨率、回波功率、信杂比和信噪比对熔岩管探测雷达进行了参数优化设计，建立了仿真系统，利用伪谱时域方法对不同走向的月球熔岩管回波进行了仿真研究 ...
马 士璇 +4 more
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Gaoya dianqi, 2021 根据输电导线覆冰后高频激励融冰的物理过程,基于传热学理论分析了高频激励融冰的热平衡过程,建立高频激励临界融冰条件的物理数学模型,分析了影响高频激励临界电流的主要因素,应用有限元软件Ansys对临界融冰电流的影响因素进行了仿真分析与验证。分析结果表明:高频激励临界融冰电流与环境温度、风速和覆冰厚度有关,环境温度越低或风速越大高频激励临界融冰电流越大,覆冰厚度对高频激励临界融冰电流影响较小。因此选择适当融冰时机对有效提高高频融冰效率具有重要意义。
彭志勇 +5 more
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E o palhaço o que é? É uma mulher
Arteriais - Revista do Programa de Pós-Gradução em Artes, 2019 ResumoEste ensaio traz a fala de uma mulher que descobre em si um palhaço, mesmo atuando, há 13 anos, como palhaça. O encontro com o palhaço Uisquisito ocorreu em 2012, no grupo de teatro Palhaços Trovadores, do qual faço parte há 10 anos. A partir disso, atuar na palhaçaria com gêneros diferentes, feminino e masculino, trouxe-me reflexões não só na ...
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Gaoya dianqi, 2021 电缆的传播常数、特征阻抗、相速度的高频特性表征了电缆的高频传输特性,而准确获取电缆的高频传输特性是电缆故障定位的基础。文中针对现有测试技术的不足,提出了基于电缆阻抗谱的同轴电力电缆高频传输特性获取方法,研究结果表明:在300 kHz～100 MHz频率范围,随着频率的增大,衰减常数和相移系数近似线性增大;相速度随频率的增大略有增加,并趋于稳定值;受测量接线处附加电感和附加电容的影响,特征阻抗的高频特性出现较为严重的畸变。
张丹丹 +7 more
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Pensando - Revista de Filosofia, 2017 Não parece haver, ao menos num primeiro olhar, qualquer ponto de convergência entre a literatura de Lampedusa e a filosofia de Kierkegaard. Contudo, com um pouco mais de investigação, tal percepção revela-se falsa. Ambos os autores se situam no século XIX e, nesse sentido, há forte conexão entre ambos a partir de uma análise histórica, filosófica e ...
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Gaoya dianqi, 2022 高频变压器是DC/DC变换器的重要电气元件，其内部温度过高会加速绝缘老化，准确预测高频变压器的温度分布有助于其散热设计。文中考虑温度对高频变压器材料电磁特性和空气热物理特性的影响，利用Infolytica有限元软件建立高频变压器的瞬态磁场—温度场双向耦合模型，通过仿真分析，得到高频变压器的磁密分布、损耗分布和温度分布。在此基础上，根据高频变压器的散热路径建立其等效热路模型，计算出稳态温度分布。通过比较分析可知分别使用有限元法和等效热路法得到的计算结果相吻合 ...
孙晨茜, 李琳
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Institutional lessons from the Nordic management model
Conservation Biology, EarlyView.Abstract To improve wildlife management outcomes, in terms of reaching management goals and increasing legitimacy, Nordic countries have developed institutional systems involving stakeholders that aim for a more inclusive and participatory model.
Jens Nilsson +2 more
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