Results 11 to 20 of about 622,498 (214)
Gaoya dianqi, 2022 由于地磁暴在大地产生感应电流以及直流输电系统单极性运行方式与大地形成回路，使得直流电流进入变压器中性点，造成变压器直流偏磁，电流发生畸变，产生谐波。文中在已经研究过的单相特高压变压器直流偏磁计算的基础之上，以230 kV三相五柱式变压器为例，依据单相变压器和三相变压器电路、磁场的区别，利用变压器磁场模型与电路模型建立微分方程，对三相变压器的直流偏磁进行了计算分析。为使计算结果能够快速稳定，在电路中人为串联大电阻，并在计算完成后使用电压补偿的方法将串联电阻所分电压补偿在电路中，根据计算结果可知 ...
王泽忠, 郭苏鑫, 李冰, 张廉杰
doaj
Force-induced phase behavior of polymer chains(外力诱导下的高分子链相变)
Zhejiang Daxue xuebao. Lixue ban, 2009 采用nPERMis(new pruned-enriched rosenbluth method with importance sampling）算法,研究了吸附在表面的高分子链在外力诱导下的相变行为.以链长N = 60的高分子链为例,在外力的作用下相变临界温度比没有外力作用的相变临界温度要低,并随外力的增大相变临界温度降低,但比热容峰值会增大.当外力f= 1.0或者1.5时,在高温区域高分子链形状发生较大变化,但在低温区由于高分子链内部相互作用和界面的吸附作用 ...
YANGZhi-yong(杨志勇) +1 more
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Dizhen xuebao, 2020 在合成孔径雷达干涉测量中，干涉相干是局部干涉条纹质量的重要评价标准，但是由于各种失相干源的影响，会出现失相干现象，而这可能会丢失重要的形变数据。本文首先利用ENVISAT ASAR的两景影像获得了2009年意大利拉奎拉MW6.3地震的带有失相干现象的同震形变场，对数据预处理后再使用移动窗口克里金法对拉奎拉地震的同震形变场进行插值处理，恢复了形变图的失相干区域，之后进一步通过正反演获得同震形变场，并与上一步的插值结果进行对比分析。结果显示，插值结果与反演结果在极震区吻合得很好 ...
Jintian Li +3 more
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Kongjian kexue xuebao为揭示微重力条件下PCM液桥相变过程流动特征及相变演化规律, 建立PCM液桥数理模型, 采用数值模拟的方法系统研究了不同工况下PCM液桥相变过程中固液界面的演化过程, 分析不同高径比和温差对液桥形状、固液界面演化规律、相变速度和热毛细流动的影响. 研究结果表明, 在大温差条件下热毛细流动更加强烈, 处于外部壁面处的相变材料的相变速度也会更快, 外壁处的相变界面与壁面的夹角会更小. 大的高径比条件下会有同样的效果, 同时也会产生更多的涡胞结构, 热毛细对流效果更明显.
张 永春 +6 more
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Equine Veterinary Journal, EarlyView.Abstract Background The middle conchal sinus (MCS) (ethmoidal sinus) remains one of the least understood equine paranasal compartments. Despite recognition of its involvement in sinonasal disease, disorders of the MCS often remain underdiagnosed in the absence of computed tomographic (CT) imaging due to limited anatomical understanding and challenges ...
J.‐B. Pavard +3 more
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Gaoya dianqi, 2022 变压器外部噪声控制系统对提升变电站声环境质量具有重要意义。噪声控制系统的布放位置和结构参数选择需要依据变压器空间噪声的干涉衰减和频谱特性。目前对变压器不同位置噪声干涉衰减规律的研究很少。文中测量了山西省内某1 000 kV特高压变压器噪声，研究了变压器A、B、C相以及AB、BC相中间位置噪声干涉衰减规律。变压器A、B、C相声压级随测量点到变压器立面距离增加单调下降，略有波动，分为快衰减段和慢衰减段。变压器AB、BC相中间位置，由于近场干涉作用出现明显的振荡段。在振荡段高频分量单调下降 ...
张超, 刘国强, 芦竹茂, 俞华
doaj
Integrative Conservation, EarlyView.Through systematic price collection and correction for underreporting and undetected seizures, the global illegal wildlife trade (IWT) is estimated at US$28.4–39.5 billion per year. This finding highlights that previous valuations were underestimates.
Jia Hao Tow, L. Roman Carrasco
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Canine Distemper Virus Research in China and Future Directions for Conservation 中国犬瘟热病毒研究现状与保护策略展望
Integrative Conservation, EarlyView.ABSTRACT Canine distemper is a highly contagious, severe disease caused by the canine distemper virus (CDV). With a worldwide distribution and ever‐expanding list of susceptible hosts, CDV poses a growing risk for many threatened wildlife species, both in captivity and their native habitats. As a megadiverse country, China is home to myriad endemic and
Aliana C. Norris +4 more
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Integrative Conservation, EarlyView.ABSTRACT In today's rapidly urbanizing world, the survival of wildlife in cities faces significant challenges, and the attitudes of urban residents toward wildlife play a crucial role in their survival. Otters, as top predators in freshwater ecosystems who are highly sensitive to environmental changes, had once gone extinct in Shenzhen—a megacity ...
Changning Liu +5 more
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An urban evolved invasive plant tolerates experimental climate change
PLANTS, PEOPLE, PLANET, EarlyView.Urbanization may drive invasive species evolution, resulting in greater invasion risks as global conditions change. We compared urban populations of the invasive Erigeron annuus in Zagreb, Croatia, to surrounding rural populations and found that urban‐evolved populations were more tolerant of experimental warming and drought than rural populations ...
S. Luke Flory +4 more
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