Results 41 to 50 of about 12,594 (182)
Multichannel Online Lifetime Accelerating and Testing System for Light-Emitting Diodes [PDF]
, 2017 LED寿命长达数万小时，具有高效、节能、环保、高可靠性的优点，是当前国家正在提倡和推广的照明光源。然而，LED长寿命的优点却成为寿命评估的短板，需要耗费大量时间。加速寿命可大大缩短实验时间，同时也是探索LED失效机理，进一步提升LED性能的有效手段。传统的LED加速寿命方法往往采用离线测试方法，将样品连同夹具置于高温箱中，通过高温箱控制样品的整体环境温度，但是在老化过程期间需要中断老化，将样品冷却取出对其各个参数进行测试。为了更加便捷地连续性测试，一些科研机构也提出了在线测试方法 ...
肖菁菁
core
Is the US Moving Toward Autocracy? A Critical Assessment
Politics &Policy, Volume 53, Issue 3, June 2025.ABSTRACT Using the theory of incremental autocratization, I illustrate in this commentary that recent developments in the United States perfectly align with this theory. In the analytical framework I use, incremental autocratization consists of six distinct step: (1) societal turmoil, (2) a proposition of radical change, (3) an electoral victory as ...
Daniel Stockemer
wiley +1 more source
Shuitu Baochi Xuebao, 2019 以有机肥、保水剂（聚丙烯酰胺PAM、高分子吸水树脂SAP和沃特）为供试材料，通过室内土柱模拟试验，研究有机肥配施保水剂对紫色黏土水分入渗及氮素淋溶的影响。结果表明：有机肥配施保水剂可有效增加土壤的保水保肥能力，是控制土壤水分和养分淋失的有效措施。单施有机肥和有机肥配施保水剂均降低了湿润锋运移深度和入渗速率。与对照相比，单施有机肥和有机肥配施保水剂处理的湿润锋运移深度降低了33.33%~46.49%，入渗速率降低了22.73%~31.82%，累计淋溶液体积降低了1.25%~6.78 ...
蒋美佳 +7 more
doaj
, 2005 铁电陶瓷材料,特别是锆钛酸铅(PZT)在众多领域具有广泛的应用前景,影响其推广应用的主要因素是使用过程中外电、力场引起的材料性能的退化。观测铁电电畴及畴变的方法对研究其在外场下性能破坏机理、提高其使用的可靠性和预防其失效具有重要的理论和实际意义。本文比较了不同实验方法和测试技术的优缺点,对铁电陶瓷的电畴观测进行了综述,并简要总结了铁电陶瓷的畴变观测技术研究现状 ...
张颖, 张飒, 程璇
core +1 more source
Social science integration at state and federal fish and wildlife organizations in the United States
Conservation Biology, Volume 39, Issue 2, April 2025.Abstract Increasingly, conservation professionals and scholars recognize the need for more holistic integration of social science in fish and wildlife management. This call is often framed around the complexity of 21st century conservation challenges and changing societal values toward fish and wildlife and its management.
Michael R. Quartuch +7 more
wiley +1 more source
International Social Security Review, Volume 78, Issue 2-3, Page 145-171, April-September 2025.Abstract Public works programmes (PWPs) are pervasively used to tackle poverty and unemployment, and to build infrastructure and skills in low‐ and middle‐income countries. While their impacts on poverty, food security and labour outcomes have been widely documented, there is little research focusing on the role of PWPs in supporting household climate ...
Francesco Burchi +3 more
wiley +1 more source
The Influence of Tooth Flank Quality and Lubrication Conditions on the Tooth Surface Load Capactiy
Jixie chuandong, 1994 本文研究了同一种材料齿轮在不同表面质量和润滑条件时的失效机理、失效形式及相应承载能力的影响，讨论了如何更准确地控制齿轮润滑状态。
秦国珍, 杨铁军, 韩歌平
doaj
Integrative Conservation, Volume 4, Issue 1, Page 71-84, March 2025.Gaoligong Mountain is home to a large number of rare and endangered species, but the effectiveness of conservation measures in the Gaoligong Mountain Nature Reserve remains uncertain. We predicted the potential distribution areas of 361 rare and endangered wild plants in southern Gaoligong Mountain under current and future climate change scenarios and ...
Yong‐Jing‐Wen Yang +3 more
wiley +1 more source
Jianzhu Gangjiegou Jinzhan建立Levy型索穹顶结构有限元分析模型，给出有限元结果合理性的判定准则，提出冲击失效准则。进行大量冲击工况下的动力响应全过程分析，给出杆件破坏分布规律和失效模式，揭示在竖向冲击荷载作用下的失效机理。依据冲击失效机理及参数分析，提出抗冲击措施。研究结果表明：所有冲击工况均符合冲击判定准则，在所选竖向冲击荷载范围内，Levy型索穹顶结构的失效模式分为4种，即结构轻度损伤、结构局部1级失效、结构局部2级失效和结构整体破坏。随着冲击动的增加，结构的动力响应模式逐渐呈模式1→模式2→模式3→模式4发展趋势 ...
高占远, 朱佳静, 薛素铎, 阮冬
doaj +2 more sources
Dianci bileiqi, 1992 探讨了将扫描电子显微镜的电压衬度象用于ZnO压敏电阻的晶界现象、导电机理及其失效机理研究的可行性,从而提供了一种新的分析手段.
岳瑞峰, 李能贵, 邢朝至
doaj