Results 21 to 30 of about 6,512 (130)

考虑接触电压的风电机组接地网优化设计

open access: yesDianci bileiqi, 2013
为确保风电场电气设备和工作人员人身安全,接地设计需要有合格的接地电阻值、接触电压和跨步电压值。在接地电阻满足安全值的情况下,如果接地设计不合理,地面上还是可能产生超过允许值的接触电压和跨步电压。降低接触和跨步电压的一般方法是增设水平接地网和在地表铺设高阻率土壤层,但风电机组所处自然环境特殊,受地形限制,不易过多扩大接地网面积。在不增加接地网总长度的情况下采用不等间距法布置地网导体,或者改变地基与接地网的相对位置可显著降低地表最大接触电压,提高地网安全水平 ...
宋景博   +4 more
doaj  

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

接地网接地电阻小比例模型试验与修正研究

open access: yesDianci bileiqi, 2017
基于接地网小比例模型试验原理,以某水电站为例,在自动化电解槽中采用琼脂和稀释盐溶液作为导电介质进行了接地网小比例模型试验。借助CDEGS软件分析了本试验结果对评估实际接地网接地电阻所起的作用,结果表明,接地网小比例模型试验中导体半径对接地电阻影响较大。本文引入接地网接地电阻小比例模型试验半径修正系数概念,从导体半径、模拟地网面积以及模拟地网网孔数目等方面分析对其的影响,根据分析结果,对本次模拟试验测量得到的接地电阻进行修正,修正后得到的原接地网接地电阻与实际接地网接地电阻较符合 ...
彭永晶   +4 more
doaj  

Beyond Motivation: Modeling the Predictive Role of L2 Pride in Informal Digital Learning of English

open access: yesInternational Journal of Applied Linguistics, Volume 35, Issue 4, Page 1938-1952, November 2025.
ABSTRACT This study investigates the role of second language (L2) pride—an understudied affective factor—in shaping learners’ language learning motivation and involvement with informal digital learning of English (IDLE). Drawing on questionnaire data from 1388 Chinese university EFL students, the study employs structural equation modeling to examine ...
Minlin Minny Zou   +3 more
wiley   +1 more source

大型变电站接地网雷电冲击暂态特性的仿真

open access: yesDianci bileiqi, 2019
为了更深入掌握雷电冲击下大型变电站接地网的暂态特性,指导变电站的防雷接地设计,建立了大型变电站雷电冲击暂态特性的仿真模型。在此基础上,使用矩量法(MOM)在不同土壤电阻率、不同地网边长、不同网孔大小以及不同雷电流波头时间等情况下分别进行了接地网的雷电冲击暂态特性的仿真计算。结果表明:土壤电阻率越大,接地网的冲击接地特性越呈现出阻性;地网面积越大,接地网的冲击接地特性越呈现出感性;网孔大小对接地电阻的影响不明显,当网孔边长从50 m下降到10 m时,接地网的工频接地电阻与冲击接地电阻分别下降了22.95 ...
李冠华, 金鑫, 赵义松
doaj  

How to talk about crises? Leaders' narrative strategies during the COVID‐19 vaccination campaign in Italy and France

open access: yesPolicy Studies Journal, Volume 53, Issue 4, Page 994-1013, November 2025.
Abstract Defined by threat, urgency, and uncertainty, crises produce opportunities for government leaders to exploit and create meaning around their policy decisions in such unstable circumstances. In narrating their preferred policy solutions, one of the tools governments can use is relying on evidence‐based information.
Laura Mastroianni, Stefania Profeti
wiley   +1 more source

Reproductive outcome after frozen embryo transfer with hormone replacement therapy according to luteal‐phase support protocol: systematic review and network meta‐analysis of randomized controlled trials

open access: yesUltrasound in Obstetrics &Gynecology, Volume 66, Issue 4, Page 422-432, October 2025.
ABSTRACT Objective To compare reproductive outcome between luteal‐phase support (LPS) protocols for frozen embryo transfer (FET) cycles with hormone replacement therapy (HRT). Methods A search was conducted in MEDLINE, Scopus, LILACS, EMBASE, Scielo.br, PROSPERO, CINAHL, PsycINFO, AMED, ClinicalTrials.gov, ICTRP, the Cochrane Library and conference ...
A. Etrusco   +11 more
wiley   +1 more source

接地模块对地网接地电阻的影响

open access: yesDianci bileiqi, 2008
介绍了非金属接地模块的组成以及降阻原理,利用接地网仿真计算模型,分析了接地模块的安装位置,接地模块个数,接地网面积以及土壤电阻率等条件发生变化时接地电阻的变化规律。地网散流时,在地网边角上的电流最大,接地模块最佳的安装位置是地网的边角;相同的接地模块对不同面积地网的降阻效果是不同的,地网越小,降阻效果越好;接地模块之间会产生屏蔽现象,影响降阻效果;土壤电阻率越高,接地模块的降阻效果越明显;在不同土壤电阻率的情况下,使用接地模块而产生的地网接地电阻下降率是相同的。
周炜明   +4 more
doaj  

Moderate time grazing in the warm season maintained the diversity and complexity of soil microorganisms by regulating nutrient cycling and decomposition function

open access: yesFunctional Ecology, Volume 39, Issue 10, Page 2772-2789, October 2025.
Read the free Plain Language Summary for this article on the Journal blog. Abstract The soil microbial community plays an important role in maintaining the functional balance of grassland ecosystems. However, it is unclear how soil microbial diversity and complexity change in the desert steppe under different grazing times and what ecosystem factors ...
Zhuo Liu   +7 more
wiley   +1 more source

基于回声状态网络的接地网地表电位计算

open access: yesGaoya dianqi, 2019
现有基于地表电位的接地网故障诊断需要测量大量的现场数据,为在减少现场测试工作量的同时提高接地网地表电位分布计算的准确性,文中提出了基于回声状态网络的接地网地表电位计算方法。首先利用接地网地表电位计算结果对回声状态网络进行训练,然后根据接地网结构对其进行网孔划分,最后使用少量的现场测试数据输入到每个区域的回声状态网络模型来计算得到接地网的整体地表电位分布。计算结果与某接地网模型的试验结果表明,文中所提方法能得到特定网孔处的接地网地表电位分布计算模型,据此可得到较为准确的接地网地表电位分布 ...
盛青   +5 more
doaj  

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