Results 71 to 80 of about 19,278 (163)

永磁机构真空断路器合闸特性受温度影响的研究

open access: yesGaoya dianqi, 2017
同步关合工作中,环境温度变化会造成开关动作分散性的加大。文中研究环境温度改变时,影响断路器合闸动作特性的主要因素的变化规律及机构合闸特性的变化。拟合实验数据,得到该结构参数下单稳态永磁机构真空断路器合闸时间与影响因素间的经验公式。研究表明:环境温度改变时,断路器运动部件静态受力(包括静态吸合力及阻尼)是影响断路器合闸特性的主要因素;同时,电容等效串联电阻低温下对断路器合闸特性也有着较大影响。经验公式可以很好地表征各变量与合闸时间的关系,对同步关合技术研究有一定帮助。
王仁丽, 晁雪薇, 田宇, 曾小平
doaj  

Effects of political identity activation and inaccurate metaperceptions on attitudes toward wolves

open access: yesConservation Biology, EarlyView.
Abstract Polarization between groups can undermine durable conservation outcomes. Activating group identities (i.e., an individual's sense of self derived from membership in a group) can exacerbate differences, especially when people hold inaccurate perceptions of their peers and rivals.
Alexander L. Metcalf, Justin W. Angle
wiley   +1 more source

Evaluating the empirical basis for threat attribution in the IUCN Red List

open access: yesConservation Biology, EarlyView.
Abstract Understanding the impacts of different threats on species is key to successful conservation interventions and policies. The International Union for Conservation of Nature (IUCN) assesses threats to species, and the organization's Red List of Threatened Species is a key conservation tool.
Ena Humphries   +5 more
wiley   +1 more source

直流接触器分闸动作特性的建模仿真研究

open access: yesGaoya dianqi
直流接触器是一种集机械、电气等多学科领域的控制元件,在新能源和电动汽车领域中得到了广泛应用,而建模仿真是对直流接触器进行数字化设计的一种有效方法。直流接触器的分闸动作主要依靠其反力系统完成,反力系统在直流接触器电磁系统线圈断电后,接触器内部的电磁吸力消失,整个系统受到重力以及触头弹簧与反力弹簧反力的作用,动铁心连带动触头朝着与合闸相反的方向运动从而完成分闸过程。分闸动作特性是衡量直流接触器性能的重要指标,利用软件仿真能快速得到接触器的分闸动作特性,从而降低直流接触器的设计优化成本 ...
鄢呈旸   +3 more
doaj  

An experimental approach to assess the combined effects of multiple stressors on a large vertebrate species

open access: yesConservation Biology, EarlyView.
Abstract The design of experiments to investigate the combined effects of multiple stressors requires exposing target organisms to multiple combinations of stressor doses. Concurrent manipulation of stressors is often infeasible with wildlife, but long‐lasting health effects allow individual health to be used as an integrator of prior stressor exposure.
Enrico Pirotta   +24 more
wiley   +1 more source

Calibration of the species threat abatement and restoration metric's threat abatement component in a Costa Rican landscape

open access: yesConservation Biology, EarlyView.
Abstract Achieving global conservation policy goals requires the ability to set and measure progress toward science‐based targets for biodiversity. The species threat abatement and restoration (STAR) metric was developed to enable actors to set science‐based targets for species.
Louise Mair   +17 more
wiley   +1 more source

Profiling EFL Students’ Motivation and Anxiety in Collaborative Learning: Associations With Teachers’ Support, Self‐Regulated Learning, and Achievement

open access: yesInternational Journal of Applied Linguistics, EarlyView.
ABSTRACT Previous research has established the relationships between motivation, anxiety, teachers’ support, and self‐regulated learning (SRL) in English‐as‐a‐foreign‐language (EFL) learning. Most of the studies, however, have taken a variable‐centered approach in addressing the variable correlations, while learners’ characteristics and variable links ...
Yuhong Jiao, Barry Bai, Jing Li
wiley   +1 more source

一起特殊故障的继电保护动作行为分析

open access: yesGaoya dianqi, 2002
介绍一起由线路故障引起220kV母线母差保护动作的特殊故障,结合保护、母差保护动作情况及故障录波图,分析推断了故障的发展过程及线路、母差保护动作的正确性。
林俊昌
doaj  

How Do I Measure up? Social Influence and L2 Motivation in the Algorithmic Age

open access: yesInternational Journal of Applied Linguistics, EarlyView.
ABSTRACT Comparative thinking is a fundamental human drive and a hallmark of contemporary life. For social action, such as the learning and use of additional languages, a target for appraisal (an L2 attribute) is evaluated in relation to a comparison standard (an appraiser's standpoint).
Alastair Henry, Meng Liu
wiley   +1 more source

压气式SF6断路器动态运动特性的研究

open access: yesGaoya dianqi, 1983
本文分析了压气式SF6断路器的静态与动态运动特性的区别,考虑了电弧电流对运动特性的影响,引进了电弧截面影响系数δ和电弧温度系数Ω。然后应用焓流理论求取了电弧面积,导出了负载下电气室气体密度,压力特性及断路器分闸特性计算式。最后以LW—220落地箱式SF6断路器为例进行了计算,并与试验结果作了比较。
施文耀
doaj  

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