Results 11 to 20 of about 1,069,594 (157)
Zhejiang Daxue xuebao. Lixue ban, 2019 压缩感知理论中降低信号维数的关键问题是构造有效的测量矩阵。在已知稀疏基的情况下，基于ETF （Equiangular Tight Frame） 框架的测量矩阵构造方法和稀疏信号重构过程均依赖于感知矩阵。为此，设计了一种基于共轭梯度法的感知矩阵优化方法，该方法简单易行，且所求结果的Gram 矩阵与目标Gram 矩阵更接近。实验结果表明，此感知矩阵优化方法在理论分析、实际图像应用及算法有效性上均具优势。
LIXinyi(李昕艺) +2 more
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Zhejiang Daxue xuebao. Lixue ban, 2022 为加快张量积型Said-Ball曲面渐近迭代逼近法的收敛速度，探讨了张量积型Said-Ball曲面渐近迭代逼近法的预处理技术。首先利用对角补偿约化技术构造了预处理子，然后结合矩阵Kronecker积性质，采取预处理渐近迭代逼近法求解张量积型Said-Ball曲面。为进一步降低计算量并提高算法的稳定性，利用广义极小残差法求解预处理方程，得到预处理渐近迭代逼近法的非精确求解方法。分析了预处理渐近迭代逼近法及非精确求解方法的收敛性。最后用数值实例说明预处理子能大大减小迭代矩阵的谱半径 ...
QUANHaorong(全浩荣) +4 more
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Conservation Biology, Volume 37, Issue 1, February 2023., 2023 Abstract Invasive species can dramatically alter ecosystems, but eradication is difficult, and suppression is expensive once they are established. Uncertainties in the potential for expansion and impacts by an invader can lead to delayed and inadequate suppression, allowing for establishment.
Brian D. Healy +5 more
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soundscape_IR: A source separation toolbox for exploring acoustic diversity in soundscapes
Methods in Ecology and Evolution, Volume 13, Issue 11, Page 2347-2355, November 2022., 2022 Abstract Soundscapes contain rich acoustic information associated with animal behaviours, environmental characteristics and human activities, providing opportunities for predicting biodiversity changes and associated drivers. However, assessing the diversity of animal vocalizations remains challenging due to the interference of environmental and ...
Yi‐Jen Sun +2 more
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Conservation Biology, Volume 36, Issue 2, April 2022., 2022 Abstract There is increasing interestin broad‐scale analysis, modeling, and prediction of the distribution and composition of plant species assemblages under climatic, environmental, and biotic change, particularly for conservation purposes. We devised a method to reliably predict the impact of climate change on large assemblages of plant communities ...
Alessandro Ferrarini +3 more
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Journal of Mathematics, Volume 2021, Issue 1, 2021., 2021 Fractional order research has interdisciplinary characteristics and has been widely used in the field of natural sciences. Therefore, fractional order research has become an important area of concern for scholars. This paper used 2854 literatures collected from China National Knowledge Infrastructure (CNKI) database from 2001 to 2020 as the data source
Yunfei Yang +4 more
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Fitting and fairing quad-meshes by matrix weighted NURBS surfaces(矩阵权NURBS曲面的拟合与光顺)
Zhejiang Daxue xuebao. Lixue ban, 2023 介绍了利用矩阵权非均匀有理 B-spline（non-uniform rational B-spline，NURBS）曲面拟合与光顺带法向的网格数据。通过输入带法向的规则四边形网格，以网格的顶点为曲面的控制顶点，用法向信息计算每个控制顶点对应的矩阵权，构造矩阵权NURBS曲面。与传统NURBS曲面相比，矩阵权NURBS曲面具有拟柱面精度，当数据均匀采样自光滑曲面时，构造的矩阵权NURBS曲面具有较好的光顺性且能很好地拟合网格模型；当输入的网格数据掺杂噪声时 ...
董国鑫(DONG Guoxin) +1 more
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Dianci bileiqi, 2022 针对传统接地网接地阻抗计算方法计算量大、准确率低的情况，笔者基于场路耦合理论和矩量法提出了一种钢制接地网的数值计算方法，该方法考虑了回出线架空地线、导体的电阻和自感以及导体之间的互感，同时还考虑了钢的磁导率饱和度的非线性特征。笔者所提方法首先由基尔霍夫电流定律和欧姆定律联立方程得出基于回出线影响下的阻抗，然后通过接地网节点模型建立阻抗矩阵。通过矩点匹配法化简矩阵并求解，多次迭代得出阻抗，最终取两者阻抗的平均值为最终的阻抗。与传统方法相比，本计算方法计算量低、准确率高。实验测试表明，随着短路电流的增大 ...
李国胜, 郑雪, 罗福玲
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Dizhen xuebao, 2022 研究了构建时域谱单元质量特性模型的数学机制，针对时域切比雪夫谱单元和勒让德谱单元建立了一种直接导出谱单元一致质量矩阵和集中质量矩阵的统一数学方法，对比分析两种谱单元质量特性模型的特征，并从物理角度探讨了谱单元质量特性模型的合理性。研究表明，数值积分点与谱单元节点选取是否一致是决定时域谱单元形成一致质量模型或集中质量模型的根本原因，当采用高斯-勒让德积分计算谱单元质量模型时将导出一致质量矩阵，而采用高斯-洛巴托积分则导出集中质量矩阵。而集中质量模型更具有物理合理性，两种谱单元质量特性模型优劣相当 ...
Hongjing Li, Jingxiong Wang
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Zhejiang Daxue xuebao. Lixue ban, 2017 在压缩感知理论中，广义正交匹配追踪(gOMP)算法常用于解决l0范数的最小化问题.借助无噪声干扰的压缩感知观测模型，提出了循环码差错图案E重构的压缩感知模型，以校验矩阵H作为测量矩阵，伴随式S作为测量信号，采用gOMP算法重构了差错图案E，其与收码R进行模2加运算，求得发码C的估值.进一步提出了校验矩阵H作为测量矩阵的构成形式及其2个定理.详细论述了gOMP算法重构差错图案E的计算过程.以(7，1)、(7,3)、(7,4)、(15，7)和(31，21)循环码为例，分析了gOMP算法对循环码的纠错能力；以(
JIANGEnhua(姜恩华)
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