Results 11 to 20 of about 1,174,075 (153)
Use of carrion fly iDNA metabarcoding to monitor invasive and native mammals
Abstract Severely fragmented habitats increase the risk of extirpation of native mammal populations through isolation, increased edge effects, and predation. Therefore, monitoring the movement of mammal populations through anthropogenically altered landscapes can inform conservation. We used metabarcoding of invertebrate‐derived DNA (iDNA) from carrion
Kristen Fernandes +5 more
wiley +1 more source
矿用高压电缆在实际使用中易受电、热、机械应力等多种因素的复合作用,加速绝缘老化,易导致电缆漏电、短路或放电等故障。目前,介电响应法被引入矿用电缆绝缘性能及老化状态的分析、评估和诊断中。针对基于介电响应法的电缆绝缘性能及老化状态评估问题,以常用的三元乙丙橡胶(EPDM)绝缘矿用移动软电缆为研究对象,总结了介电响应法中回复电压法、极化/去极化电流法和频域介电谱法的基本原理和典型特征量,对比了3种方法的优缺点。介绍了扩展Debye模型提取的老化因子、修正介电驰豫模型提取的弛豫特征量 ...
李蔚 +6 more
core +1 more source
随着动车组服役年限的增加,其车顶绝缘子的绝缘性能会发生衰退。为研究不同服役年限下高压隔离开关用绝缘子性能衰退特性,本研究以动车组车顶复合支柱绝缘子为研究对象,对其进行了憎水性、绝缘电阻测试和雷电冲击试验。基于绝缘子憎水性测试,研究表明,服役年限为3年的绝缘子憎水性最好,为HC3级。与服役年限为3年的绝缘子相比,服役年限为4年、5年、6年和10年的绝缘子憎水性普遍下降,均为HC4-HC5左右;基于绝缘子绝缘电阻测试,研究表明,不同服役年限下绝缘子泄漏电流变化不大,均维持在30.6μA~42.0μA ...
于治国 +5 more
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6.3~40.5 kV干燥空气开关柜绝缘件阻燃性的实验分析与研究
绝缘件是6.3~40.5 kV空气绝缘开关柜设备中的薄弱环节,其中环氧树脂绝缘件在设备中应用较多,其性能直接决定开关设备的绝缘性能及运行可靠性。环氧绝缘件一般采用双酚A环氧树脂和固化剂经过复杂的化学反应制成,不同制备条件、工艺等对绝缘件的使用性能有很大影响。文中通过不同配比的环氧树脂样品的实验分析和研究,得出了玻璃化转变温度、填料、耐电痕性能等对绝缘件阻燃性的影响,对绝缘件的加工和制造有一定的指导意义。
袁培 +5 more
doaj
We collated detections of the sun bear from new and previously published camera trap studies across its range. We then analysed these detections at two different spatial scales to assess the habitat associations and diel activity of this species. We found that the sun bear is tolerant to moderate habitat disturbances. ABSTRACT Degraded tropical forests,
Alexander Hendry +5 more
wiley +1 more source
圆柱头和圆锥头盘形悬式瓷绝缘子的内、外绝缘性能在理论上无本质差别。相比圆锥头瓷绝缘子,圆柱头瓷绝缘子重量明显减轻,可有效降低杆塔导线的机械载荷;并且对于材料性能经时变化有较好的分散和调整能力,使得产品不受过大应力及不均匀应力的长时作用,具有较高的可靠性。为进一步提升圆柱头绝缘子产品的机械性能,笔者在不改变绝缘子铁帽及瓷件结构的前提下,建立了钢脚参数化的精细仿真模型,通过有限元法计算分析钢脚几何参数对圆柱头瓷绝缘子机械性能的影响,为产品优化提供设计参考。
周学明 +6 more
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The Two Faces of Introgression in Conservation Biology 基因渗入在保育生物学中的双重面貌
Conservation biologist need to take into account the various aspects of introgression in their attempts to protect the species integrity and evolutionary potential of threatened species. To do so, they have to overcome the bias created by the Mayrian species concept that considers species as having distinct gene pools.
Harald Schneider, Charles H. Cannon
wiley +1 more source
Abstract In the armed conflict between Kashmiri militancy and the Indian state forces, Kashmiri women have been relentless victims of abduction, rape, molestation, and cruel objectification by the militaristic patriarchs of both sides. In the context of the state's unaccountability, the rebuttal of justice is horrific in Kashmir.
Payel Pal, Goutam Karmakar
wiley +1 more source
Core concerns: The need for a governance framework to protect global Internet infrastructure
Abstract The war in Ukraine has underscored the risks and threats to global Internet infrastructure from geopolitically motivated cyber operations. The Domain Name System and core protocols responsible for the routing, forwarding, and security of Internet traffic have been exploited by actors in Russia and Ukraine for denial‐of‐service attacks ...
Dennis Broeders, Arun Sukumar
wiley +1 more source
复合绝缘子是绝缘材料在电力系统外绝缘应用之一,其绝缘老化性能与表面憎水性有密切关系,因此需要对其绝缘老化判断方法进行研究。本文提出了一种基于支持向量量机(SVM)的复合绝缘子硅橡胶材料绝缘老化性能的判断方法。支持向量机以结构风险最小化为原则,统计学习训练为基础,具有较强的泛化能力。该文以最大水珠形状因子、面积比等特征参数为输入,硅橡胶材料的绝缘老化性能为输出,建立特征参数与绝缘老化性能间的关系。实验结果表明:该方法能判断出复合绝缘子硅橡胶材料绝缘性能良好、正常、差3种状态,尤其以最大水珠面积比为输入时 ...
何贵, 廖平军
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