Results 11 to 20 of about 8,663 (187)
Dizhen xuebao, 2022 地震动合成方法的应用前景与其所能表达的有效频带范围紧密相关。本文研究基于频率波数域格林函数的地震动合成方法（FK法），分析频带范围的关键影响要素及处理措施。在介绍计算原理的基础上，概括FK法合成地震动的主要影响要素，分析地壳速度模型对子源地震矩、破裂时间和传播时间的影响。随后，分析格林函数传播宽频带地震波的能力，提出格林函数计算中的频带影响参数的建议值。为分析FK法的震源模型辐射宽频带地震波的能力，重点考察控制子源错动过程的震源时间函数和上升时间。研究认为，FK法具有合成宽频带地震动的能力 ...
Zelin Cao +3 more
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Fast blind detection of short-wave frequency hopping signal based on MeanShift [PDF]
, 2022 In the complex short-wave channel environment, combined with time-frequency analysis technology, a fast blind detection algorithm of the connected domain labeled frequency hopping signals based on MeanShift algorithm was proposed to reduce the influence ...
Jing LIANG +6 more
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Multi frequency hopping network station sorting based on joint feature clustering in complex environment [PDF]
, 2023 In order to remove interference from hybrid signals and sort each frequency hopping station signal, a multi frequency hopping network station sorting algorithm based on joint feature clustering was proposed.Firstly, short-time Fourier transform was ...
Jiazheng WANG +4 more
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Short wave protocol signals recognition based on Swin-Transformer [PDF]
, 2022 Aiming at the problem that it is difficult to identify the protocol to which the signal belongs in the complex SW channel environment, a SW protocol signal recognition algorithm based on Swin-Transformer neural network model was proposed.Firstly, the ...
Di WU +5 more
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Time-frequency analysis of freqency-hopping signals based on sparse recovery [PDF]
, 2013 To overcome the common shortcomings shared by the existing methods: weak suppression noise interference and feeble performance of time-frequency concentration,a novel time-frequency analysis method based on sparse repre-sentation was developed,which ...
Jun-hua WANG +3 more
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基于小波变换的2013年芦山MS7.0地震前姑咱台钻孔应变异常时频分析
Dizhen xuebao, 2019 2013年4月20日芦山MS7.0地震前，四川省姑咱台四分量YRY-4型钻孔应变仪记录到显著的高频应变畸变信号。为了避免该畸变信号的高频部分在时频演化过程中发生频率混叠现象，同时便于讨论同一研究频段内震前更早记录到的弱应变异常时段与显著应变异常时段的相关性，本文对2012年1月1日至2013年4月20日期间姑咱台的钻孔应变数据进行了时频分析，并使用时域分段的小波变换方法，在局部时频谱中提取了应变异常，分析了各应变异常的频率相关性。结果表明，研究频段内存在两个峰值频率 ...
Weichen Zhang +4 more
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我国医学科学评价领域研究结构现状分析———基于近十年医学评价研究论文的计量学分析
实用医学研究, 2020 目的:检索2010至2019年十年间医学领域的评价论文,分析该主 题 的 研 究 结 构,包 括 作 者、机 构 以 及 研 究 热 点。方法:检索CNKI数据库内医学领域评价论文,利用书目共现分析系统(BICOM)对近作者、关键词等进 行 频 次 统 计,同 时 生 成 关键词共词矩阵,并利用SPSS 22进行聚类分析,进而分析该主题研究热点。结果:共纳入有效文献2060篇;涉及作者4972位,发文量4篇以上高产作者71位;统计出关键词2962个,出现12次以上的关键词56个;关键词聚类分析 ...
克宇 姚 +4 more
semanticscholar +1 more source
Application of invariant moment method for HAPS ISAR imaging with micro parts [PDF]
, 2013 To resolve the micromotion in the HAPS(high altitude platform station) ISAR system,the invariant moment method for ISAR imaging with micro parts was proposed.Firstly,invariant moment tool was applied to classify the echoes of different sub-aperture,and ...
Hai-bin SUN +3 more
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Non-stationary signal combined analysis based fault diagnosis method [PDF]
, 2020 Considering the complementarity between the deep learning,spectrum and time frequency analysis methods,a multi-stream framework was designed by combining the convolutional network,Fourier transform and wavelet package decomposition methods,with the aim ...
Huimin LU +4 more
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Application of iterative generalized short-time Fourier transform to fault diagnosis of planetary gearboxes [PDF]
, 2017 Due to the effect of the modulation part, the energy diffuses around the surrounding area of dominating frequencies and diminishes the readability of the time-frequency representation when short-time Fourier transform (STFT) is used to process ...
FENG Zhi-peng, ZHANG Dong
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