Results 21 to 30 of about 990,138 (190)
Gaoya dianqi, 2021 基于非参数检验的声信号时域特征识别是一种高识别率、小时间开销的高压断路器机械故障诊断方法,但也有无效区间长、特征测量值和检验方法有待优化等问题。对于高压断路器机械故障声信号,根据非参数检验的效果剔除低效区段;利用散布矩阵对比特征测量值的分类能力;搭建高压断路器机械故障试验平台,对采集到的声信号分别进行4种非参数检验,选取特征值并进行机器学习。声信号的纯噪音部分和余震部分被剔除,从而得到有效时域区段;在8种特征测量值中,各种熵的分类能力明显高于均值等传统特征测量值,且Renyi熵的分类能力最好 ...
易林 +6 more
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Intact coastal nursery rearing amid climate‐driven phenological shifts in threatened salmon
Conservation Biology, EarlyView.Abstract Literature linking phenology to climate has proliferated in recent decades and shows that climate change has reorganized seasonal opportunities worldwide. However, this literature often quantifies changes in point measures of timing (e.g., beginnings and peaks) without context about duration (e.g., rearing season length) or performance (e.g ...
Stuart H. Munsch +8 more
wiley +1 more source
Gaoya dianqi, 2019 为提高基于振动信号的变压器状态识别准确率,提取振动信号的峰峰值、均值、偏度等时域特征量和主频率幅值占比、基频幅值占比、50 Hz及其奇次倍频幅值占比等频域特征量构成特征向量,运用支持向量机（SVM）分类方法对变压器进行状态识别。采集了变压器正常与故障运行状态下的振动信号,结合实测信号分析了各特征量随变压器状态的变化,最后对比了单个特征量与多特征量结合对变压器正常短路、正常空载、故障短路、故障空载4种状态的识别准确率。结果表明 ...
武立平 +5 more
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Genomics‐informed management of ex situ populations
Conservation Biology, EarlyView.Abstract The European Association of Zoos and Aquariums (EAZA) manages insurance populations for hundreds of species through its EAZA ex situ programs (EEPs). EEPs help safeguard against extinction in the wild and provide source populations for genetic rescue programs.
Cock van Oosterhout +8 more
wiley +1 more source
Dianci bileiqi, 2016 绝缘子发生污秽放电时的声信号中含有大量能够体现绝缘子污秽程度的信息量,利用傅里叶变换（FFT）将声信号分解为时域和频域两部分,研究在不同污秽度下声信号的时频特性,发现声信号的时域的平均值和频域的频谱特性两方面含有4个特征量,这4个特征量充分体现了绝缘子污秽放电的发展特征。分析得出,声信号时域的均值、最大值、标准差及FFT实部幅值这4个特征量与绝缘子污秽度具有很好的关联性,但是4个特征值对污秽预测结果的影响不尽相同。试验结果表明,绝缘子污秽放电声信号的4个特征量可以作为新的污闪预警特征量。
王洪坤, 聂晶
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Correlation of Sensory Characteristics and Price of Imported Dry Red Wines(进口干红葡萄酒的感官质量与价位的关联分析) [PDF]
Shipin kexue jishu xuebao, 2015 The sensory evaluation of imported dry red wines aims at selecting the characteristics that influence the ultimate sensory quality. Well-selling wine samples belonging to the price category of 100-600 ￥ were selected randomly from the imported wine ...
LI Wei(李 伟) +3 more
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Conservation Biology, EarlyView.Abstract The sustainability of area‐based conservation initiatives depends on their value to society. Conservation often focuses inside protected areas, but the impacts of protected areas beyond their boundaries (spillovers) are critical for their social license.
Ilaria Gliottone +5 more
wiley +1 more source
Gaoya dianqi, 2014 基于绝缘子泄漏电流可以有效预测绝缘子的污秽度,污闪、冰闪发生的可能性以及绝缘材料的老化状况,绝缘子泄漏电流特征量的提取和选择对其外绝缘状况以及材料老化状况预测的准确性具有重要影响。针对绝缘子泄漏电流特征量提取及应用方面的研究开展得已经非常广泛,非常有必要进行系统地综述。笔者对泄漏电流应用于绝缘子污秽度、污闪及冰闪电压预测、绝缘材料老化状况监测几个方面进行了系统地综述,将泄漏电流特征量分为幅值类特征量、波形及谐波类特征量和其它常见特征量3大类,系统介绍了各个特征量的研究进展 ...
苗鹏超, 徐志钮
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New Phytologist, EarlyView.Whole‐genome duplication enhances gray mold resistance in autotetraploid Fragaria nilgerrensis through coordinated gene‐dosage effects, DNA methylation remodeling, and cell‐type‐specific transcriptional reprogramming. Summary Whole‐genome duplication (WGD) triggers genetic and epigenetic remodeling that confers stress adaptation in plants, but how ...
Qiang Cao +12 more
wiley +1 more source
Shiyou jixie, 2014 针对石油井架损伤位置识别问题，提出了基于ITD与排列熵的损伤位置特征提取方法。利用ITD方法将锤击响应振动信号分解为一系列PR分量，PR分量更能突出损伤位置信息，计算PR分量的样本熵值，形成的特征向量可分性良好。依据相关性系数选择代表损伤状态主要信息的PR分量，计算其排列熵形成有效的特征向量。以支持向量机为特征向量模式识别器，对比了ITD与近似熵方法所提取特征向量，对于相同有限数量的样本，ITD与样本熵特征向量明显高于ITD与信息熵特征向量的识别率，验证了ITD样本熵方法的有效性 ...
邹龙庆 +3 more
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