Results 41 to 50 of about 15,103 (157)
Gaoya dianqi, 2016 研究套管介质损耗及电容量增量测试值分布特性有利于从宏观上掌握运行高压套管绝缘健康水平。文中基于大量现场数据样本,综合采用直方图法和非参数检验法,获得了不同电压等级、不同环境温度、不同环境湿度、不同生产厂家、不同运行时间等多个维度下的运行高压套管tanδ值及电容量增量的正态分布曲线。结果表明:对早期工艺水平及运行时间越长的套管,其测试值正态分布曲线均值、标准偏差越大;不同环境湿度下运行高压套管tanδ及电容量增量的正态分布曲线差异与湿度范围有关,当环境湿度高于80%时差异性才较为明显 ...
熊俊
doaj
Gaoya dianqi, 2022 为实现变压器有载分接开关的故障诊断和状态评估，从分析有载分接开关动作时的振动信号出发，提出一种结合信息融合技术和模糊理论的故障诊断方法。根据有载分接开关的振动信号具有混沌特性，采用相空间重构方法将其映射到高维空间。然后根据相空间内相点分布的差异性，求取相点空间分布系数作为特征值。基于多传感器信息融合技术，结合相点空间分布系数，建立多通道下三维高斯型模糊集隶属函数，用以对现场测量的正常状态和3类常见故障的振动信号进行状态识别，得到较好的识别效果，可作为有载分接开关故障诊断的有力依据。
杨晓望 +7 more
doaj
Jump-Diffusion Processes with Shot Noise Effects in Option Pricing [PDF]
, 2016 在金融市场上，股票价格并不是连续的，股票价格对于意料之外的消息会产生突然向上或向下的变动，因此Merton（1976）在为金融市场上的不正常信息的到来建立模型时提出了跳跃，即跳跃扩散过程。虽然跳跃扩散过程改进了Black-Scholes模型，但仍然无法描述一些现象，如突然的信息产生的跳跃效应会随时间消失，金融时间序列数据存在的自相关性。而通过在跳跃扩散过程中加入能在数据中产生自相关性的散粒噪声，可以很好地解决上述问题，这也是带散粒噪声的跳跃扩散过程最大的优点 ...
刘萃
core
Genetic origins and climate‐induced erosion in economically important Asian walnuts
Conservation Biology, Volume 40, Issue 1, February 2026.Abstract The global climate is undergoing unprecedented changes, posing significant threats to species persistence. However, the spatiotemporal impacts on genetic diversity remain poorly understood, hindering species conservation and management. Walnuts, generally referred to as Juglans regia and J. sigillata, are economically vital in Asia, but little
Peng‐Zhen Fan +17 more
wiley +1 more source
糖尿病、冠心病患者ABCA1基因R219K多态性的频率分布特点
Zhongguo shiyan zhenduanxue, 2011 目的旨在探讨我国北方地区汉族人ABCA1基因R219K多态性的频率分布特点,对血脂水平的影响,及其与冠心病、糖尿病和糖尿病合并冠心病的关系。方法采用改良碘化钠法提取基因组DNA,聚合酶链反应限制性片段长度多态性（PCR-RFLP）法分析ABCA1基因R219K多态性。结果正常对照组ABCA1基因R219K多态性RR、RK、KK基因型频率、R等位基因频率、K等位基因频率分别为28.5%、48.6%、22.9%、52.8%、47.2%;糖尿病组分别为29.6%、63.9%、6.5%、61.5%、38.5 ...
许慧, 彭浩, 蒋莹
doaj
Bayesian Analysis of Change-point Detection in Multivariate Time Series [PDF]
, 2016 时间序列结构突变检测问题是近年来的热点之一。Harléetal.(2014)提出了一种检验多元时间序列变点的贝叶斯方法。该方法用向量R刻画序列中每一点处变点发生的情况，通过曼-惠特尼检验计算序列每一点处的p值，并由这些p值构造替代的似然函数。最后，根据替代的似然函数以及吉布斯抽样得到对向量R的估计。该方法不要求变点个数事先给定，而是将其作为模型中的变量进行估计。 本文阐述了该方法的理论，并使用该方法对由人民币名义有效汇率同比增长率、美元名义有效汇率同比增长率 ...
秦超
core
Conservation Biology, Volume 40, Issue 1, February 2026.Abstract Exploring heat tolerance and acclimation capacity can provide an effective approach to evaluating species’ sensitivity to extremely high temperatures due to climate warming. Despite some work on amphibian and reptile thermophysiological adaptation, related questions remain. We reviewed the literature to provide a synthesis of worldwide data on
Zijian Sun +8 more
wiley +1 more source
99Tcm-N(NOEt)2 Uptake Kinetics Difference among KMB17 Human Embryonic Lung Diploid Fibroblast and Different Human Lung Cancer Cells [PDF]
, 2010 Background and objective PET/CT imaging is expensive, so searching the tumor imaging agent for SPECT/CT is necessary. 99Tcm-N(NOEt)2 [bis (N-ethoxy-N-ethyl dithiocarbamato) nitrido99Tcm (V)] can be uptaken by lung cancer cells and other cells alike.
Jianming CAO, Tiekun MA, Wei JIA
core
Survival, rarity, and extinction in tropical stony corals
Conservation Biology, Volume 40, Issue 1, February 2026.Abstract Many reef‐building tropical corals are becoming rare. We considered the meaning of rarity in corals and highlighted taxa that have reached low abundances in the last few decades. The difficulties of quantifying rarity in the marine environment arise from the sheer scale and 3‐dimensional nature of the biome and the inherent challenges therein ...
Bryan Wilson, Peter J. Edmunds
wiley +1 more source
The Maximum Likelihood Estimation of Time-varying Coefficient Spatial Autoregression Panel Data Model [PDF]
, 2016 本文对扰动项存在跨时期的异方差、但不存在序列相关的时变系数空间自回归模型提出了极大似然的估计方法,并证明了该估计量的一致性,同时,证明了该估计量渐进服从正态分布,由此说明该估计量具有优良的大样本性质。同时,我们还对本文所提出估计量的小样本性质进行了数值模拟。本文研究表明,估计量虽然在N较小时偏差较大,但是随着N的不断增加,估计量偏差减小,体现了比较优良的渐进性质。同时,估计量的偏差会随着时期数的增加而变大,这说明本文所提出的估计方法适用于个体数较多、时期数较少的短面板数据。This paper ...
邓明
core