Results 31 to 40 of about 12,489 (165)
Applications of Erlang Mixtures in Insurance [PDF]
, 2017 等尺度参数的Erlang混合分布具有很多良好的性质，广泛应用于保险精算数据中。对于混合分布的参数估计，最常用的方法是期望最大化(ExpectationMaximization，简写EM)算法。Erlang混合分布的形状参数限制为正整数，这使得形状参数的估计比较困难。在本文中我们对标准的EM算法进行修改，提出广义期望最大化(GeneralizedExpectation-Maximization，GEM)算法。在EM算法的M步中对形状参数的估计不是使相应的Q函数达到最大 ...
桂文永
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Rare Metals, EarlyView.ABSTRACT Regulating negative parameters of metacomposites is mainly limited by their unclear mechanisms, which affects their practical applications in new sensing, communication, electromagnetic (EM) protection and other fields. This work proposes a dual‐functional competitive design strategy based on the waste corncob‐derived carbon/polyaniline ...
Qiuyun Yang +4 more
wiley +1 more source
Tail Risk Premium Analysis Based on Hawkes Process——Evidence from Taiwan Market [PDF]
, 2017 本文从尾部风险溢酬的角度出发，发现利用Hawkes在1971年提出的Hawkes过程来刻画资产收益率的随机过程能够更好地估计尾部风险溢酬。在总结现有方法及其有效性的基础上，本文进一步改进Xu在2014年提出的扩展的ICAPM模型，并将其运用到台湾市场来估计风险中性测度下和现实测度下的台湾市场的形状参数、跳跃强度参数和尾部风险溢酬，在估计尾部风险溢酬时，本文将尾部风险溢酬分为正跳的尾部风险溢酬和负跳的尾部风险溢酬。 在对估计出的形状参数、跳跃强度参数和尾部风险溢酬进行统计研究时 ...
徐亮
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137Cs-based Estimation of Soil Erosion and Organic Carbon Loss in Alpine Meadow Soil on Tibetan Plateau [PDF]
, 2023 [Objective] Soil erosion and its associated carbon loss in an alpine meadow on the Tibetan Plateau were quantitatively analyzed in order to provide a reference for comprehensively evaluating the impact of soil erosion and for implementing effective soil ...
Li Wenjia, Lu Haiya, Yu Shiyong
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Rare Metals, Volume 45, Issue 1, January 2026.ABSTRACT The central challenge in the development of high‐performance electromagnetic wave‐absorbing materials lies in achieving an optimal balance between impedance matching and attenuation characteristics. This is particularly critical for purely dielectric absorbers, where precise tailoring of the real (ε′) and imaginary (ε″) parts of the complex ...
Zhixiao Wang +7 more
wiley +1 more source
Characterization of mechanical properties and primary investigation of pyrolysis and sintering of polycarbosilane-derived continuous fibers [PDF]
, 2005 Hi-NicalonSiC纤维是通过先驱体法制备并已商品化的高性能连续纤维，是制备耐高温SiC/SiC复合材料的关键原材料。降低纤维中氧的含量可提高其高温使用性能，而降低纤维的直径、减少缺陷可提高其力学性能。本论文主要对Hi-NicalonSiC纤维的力学性能进行系统表征并对PCS制备连续SiC纤维的烧成工艺进行初步探索。对Hi-NicalonSiC纤维的研究结果表明：①纤维的强度服从Weibull分布；纤维的模量服从正态分布；纤维的应变服从正态分布；纤维的直径分布服从正态分布。②Hi ...
吴清良
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New Phytologist, Volume 247, Issue 5, Page 2086-2097, September 2025.Summary The importance of marine angiosperms, or seagrasses, as foundation species for marine coastal ecosystems is in marked contrast to their low species number of only 70 described taxa. Seagrass species tend to have very similar overall morphologies dictated by hydrodynamic forces of the ocean environment.
Xiaomei Zhang +14 more
wiley +1 more source
Bezier Curve with a shape parameter and error estimate for Doo-Sabin subdivision surface [PDF]
, 2006 本文共分为三章，其内容如下：第一章首先回顾了CAGD中相关的研究背景，并简要介绍了本文的主要内容。第二章首先简单介绍了B\'{e}zier曲线及其基本性质，然后引入了一类新的调配函数，定义了一类带形状参数的B\'{e}zier曲线，使曲线的形状调整变得更加容易实现。第三章主要讨论Doo-Sabin细分曲面的误差估计问题。在这章我们首先介绍了Doo-Sabin细分曲面。然后在给出一些定义和记号之后，证明了Doo-Sabin细分曲面的控制网格按指数速率收敛于极限曲面，再利用Doo-Sabin细分曲面的凸包性，
程黄和
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New Phytologist, Volume 247, Issue 3, Page 1460-1473, August 2025.Summary Podocarpus pollen morphology is shaped by both phylogenetic history and the environment. We analyzed the relationship between pollen traits quantified using deep learning and environmental factors within a comparative phylogenetic framework.
Marc‐Élie Adaimé +4 more
wiley +1 more source
Variational Bayesian Learning of Mixed Erlang Model [PDF]
, 2017 在本文中，我们关注混合厄朗模型（MixedErlangModel，MER模型）的贝叶斯变分方法应用。混合厄朗模型（MER）的多变量混合形式构成了一种通用且易于分析的分布，除此之外，该分布在在弱收敛意义上的正连续多元分布的空间中是稠密的。这些良好的性质使得混合厄朗分布适用于多变量密度估计。因此，我们为混合厄朗模型提出了一种灵活有效的拟合算法，称为CMM-VBEM算法。该算法分为两个部分，第一部分是初始值的选取CMM算法。利用K-Means聚类的方法对参数的初始值进行估计 ...
林琴
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