Results 51 to 60 of about 14,930 (156)

Predictions of southern migration timing in coastal sharks under future ocean warming

open access: yesConservation Biology, Volume 39, Issue 6, December 2025.
Abstract Projected redistribution of marine species due to ocean warming may undermine current conservation efforts. Yet, there have been few studies on how ocean warming may alter migration timing. Across 5 years of acoustic telemetry data (2018–2022), we determined environmental drivers of southward migration timing for 6 migratory shark species from
Maria H. Manz   +16 more
wiley   +1 more source

新型长寿命复合接地系统研究及应用

open access: yesDianci bileiqi, 2019
以依托国家电网公司科技项目——新型长寿命多针式垂直接地技术研究及实现为背景,基于材料团簇理论及爆炸复合技术,研制出一种新型复合接地材料,设计了一套新型复合接地系统,兼备快速放电、高效泄流、强耐腐蚀及长寿命特性,成功应用于张庄110 kV变电站接地系统。经验证,新型复合接地系统极大降低了接地电阻,满足国家标准及规范,解决了接地系统高效、安全、小型化的工程难题,为变电站或发电厂的接地技术研究提供借鉴。
孙长海   +5 more
doaj  

基于EMTP仿真和实测的接地电缆雷电过电压特性分析

open access: yesDianci bileiqi, 2021
针对目前缺少有效设备仪器和方法保护接地系统雷击浪涌的问题,文中系统化地研究了地下配电电缆中使用的接地系统的暂态特性。通过现场实验测试与EMTP仿真分析,对传统多点接地电缆系统和非捆绑式公共接地电缆系统中性线感应的雷电过电压进行了评估计算与详细比较。首先通过EMTP软件建立配电缆雷击感应电压计算仿真模型;然后通过比较实际测量结果与EMTP仿真所得到的数值结果,验证本研究所建立的仿真模型的有效性和准确性。最终,通过验证后的模型的EMTP仿真结果对雷电绝缘水平进行预测。
廖思哲, 王婉婷, 郑刚
doaj  

Design of Power Quality Surveillance [PDF]

open access: yes, 2008
随着电网规模的扩大和现代科学技术的发展,电能质量显得越来越重要。这包含两方面的内容:一方面,造成电能质量问题的因素不断增长,如以电力装置为代表的非线性负荷的使用﹑各种大型用电设备的启停等造成大量电能问题。另一方面,各种复杂的﹑精密的﹑对电能质量敏感的用电设备不断普及,如高性能家用电器﹑办公设备﹑精密试验仪器﹑精密生产过程的自动控制设备等,对电能质量的要求越来越高,从目前的现状看,可以说电能质量问题已成为严重威胁电力网及国民经济的安全﹑经济﹑高效运行的问题,并影响产品质量和人民日常生活的生活质量 ...
李永萍
core  

Identifying priority areas for conservation to promote connectivity and mitigate the impacts of anthropogenic disturbance

open access: yesConservation Biology, Volume 39, Issue 6, December 2025.
Abstract As nations seek to expand protected area (PA) networks to cover 30% of land and seas by 2030 (30×30), there is an urgent need for systematic conservation planning and spatial prioritization that considers the broad range of ecological and socioeconomic factors influencing the persistence of biodiversity.
Edmond Sacre   +2 more
wiley   +1 more source

城市架空配电线路与埋地电缆混合传输系统雷击可靠性分析

open access: yesDianci bileiqi, 2020
城市配电线路建设会存在架空线路与埋地电缆混合传输现象,需要合理分析混合传输系统雷击可靠性以进行针对性防护。通过EMTP软件建立架空线路与埋地电缆混合传输系统模型,利用事件树方法估算系统雷击可靠性,分析电缆避雷器安装方式、杆塔接地电阻、埋地电缆长度等因素对系统雷击可靠性影响,最后讨论缩短故障修复时间提高系统雷击可靠性效果。研究结果表明:埋地电缆两端均安装避雷器时,系统雷击可靠性最高,略高于仅在一端安装避雷器情况。系统雷击可靠性随着线路杆塔接地电阻或埋地电缆长度的增加而降低 ...
杨鹏   +5 more
doaj  

The Study of EMC Overall Design for Mobile [PDF]

open access: yes, 2010
随着移动终端系统的不断发展,其功能日益多样化,线路却越来越复杂,集成度也越来越高。由于手机工作频率较高,使用范围较广,涉及环境因素复杂,对EMC设计提出了较高的要求。如何让手机系统在满足自身功能的前提下,又不干扰其它电子设备,显得尤为重要。 电磁兼容(EMC,ElectromagneticCompatibility)是当今电子科技领域非常重要的一项技术。各国对手机EMC都提出一系列的标准。在中国,参照国际规范,目前国家无委和泰尔实验室的高昂的测试费用给测试和设计工作带来了很大的不便 ...
叶菁菁
core  

Fault location method for island and reef distributed power supply system based on immune model and improved immune algorithm [PDF]

open access: yes
Objective In order to improve the rapidity and accuracy of fault location for island and reef power supply systems composed of multiple distributed power sources, a fault location method based on an immune model and improved immune algorithm is proposed.
Chenghu XU   +4 more
core   +1 more source

接地变兼站用变短路阻抗基准侧的选取与保护

open access: yes, 2020
从本质上介绍了不接地系统到电阻或消弧线圈接地系统的演变过程;引出了接地变和接地变兼站用变的概念,解释了接地变、接地变兼站用变的构造和原理;遵照国家标准,并借鉴项目经验,总结了通过接地变兼站用变铭牌参数确定短路阻抗选取基准侧的方法,并且结合实例给出了详细的解释推导,奠定了接地变兼站用变的短路电流计算,继电保护整定计算的计算基础;基于确定基准侧后的短路电流计算,分析了接地变兼站用变与普通接地变的速断保护整定计算的差异,分别从躲过变压器低压侧出口三相短路 ...
志磊 辛
core   +1 more source

Video Assistant Referee(ndums): A Populist Weapon or Effective Tool to Stop Autocrats in Competitive Authoritarian Regimes in Latin America?

open access: yesLatin American Policy, Volume 16, Issue 4, December 2025.
ABSTRACT In recent years, video assistant referee systems have been increasingly used to correct unfair decisions in sports. Similarly, I argue that constitutional referendums play a corrective role in hybrid or competitive authoritarian regimes, where the electoral referee is biased and the government enjoys unfair advantages.
Muhammet Derviş Mete
wiley   +1 more source

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