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改进型盲源分离在结构模态识别中的应用 被引量:4
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作者 曹军宏 韦灼彬 刘树勇 《振动.测试与诊断》 EI CSCD 北大核心 2013年第4期689-693,729,共5页
提出一种基于量子遗传算法的二阶盲源分离识别结构模态参数的新方法,首先,对测量信号进行Hilbert变换构建分析信号;然后,采用量子遗传算法求解最优时延,利用最优时延的二阶协方差矩阵同时对角化进行信号分离,得到的混合矩阵作为模态振型... 提出一种基于量子遗传算法的二阶盲源分离识别结构模态参数的新方法,首先,对测量信号进行Hilbert变换构建分析信号;然后,采用量子遗传算法求解最优时延,利用最优时延的二阶协方差矩阵同时对角化进行信号分离,得到的混合矩阵作为模态振型;最后,对单自由度模态响应提取模态频率和阻尼比。钢框架结构实验结果表明,该方法不仅适用于实模态情况,同时适用于复模态情况,且计算简单、识别精度高。 展开更多
关键词 模态参数识别 盲源分离 量子遗传算法 时间解相关盲源分离算法 复模态
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脑光学功能成像低频振荡信号分析及其在功能映射中的应用
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作者 胡德文 黄晓斌 +1 位作者 刘亚东 周宗潭 《电子学报》 EI CAS CSCD 北大核心 2008年第10期2065-2069,共5页
在脑光学功能成像领域,传统的比差法由于受到背景低频振荡信号的影响和算法参数选择的随意性,无法有效地消除背景干扰.本文在仔细研究强0.1Hz低频振荡在脑区域分布的前提下,提出了一种基于低频振荡的比差检测方法.该方法利用0.1Hz低频... 在脑光学功能成像领域,传统的比差法由于受到背景低频振荡信号的影响和算法参数选择的随意性,无法有效地消除背景干扰.本文在仔细研究强0.1Hz低频振荡在脑区域分布的前提下,提出了一种基于低频振荡的比差检测方法.该方法利用0.1Hz低频振荡特性进行跨周期比差,极大的消除了背景图像对激活模式图像的干扰,从而有效地提高了算法的检测性能和鲁棒性.此外研究中还发现,在某些刺激加载时刻,由于比差法和基于低频振荡的比差法受低频振荡相位的影响,当算法参数选择不当时,即使在高信噪比下也无法获取好的检测效果法.为此,本文在设计了一种新的像素点时间序列选择策略的基础上,成功地将非参数化的时间解相关盲源分离算法引入到脑光学功能成像领域,从而提高了检测性能. 展开更多
关键词 脑光学功能成像 低频振荡 时间解相关
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Lump Solutions of Kadomtsev-Petviashvili I Equation in Non-uniform Media 被引量:1
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作者 朱晓明 张大军 陈登远 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第1期13-19,共7页
N-lump solutions of the Kadomtsev-Petviashvili I equation in non-uniform media are derived through the inverse scattering transform. The obtained solutions describe lump waves with time-dependent amplitudes and veloci... N-lump solutions of the Kadomtsev-Petviashvili I equation in non-uniform media are derived through the inverse scattering transform. The obtained solutions describe lump waves with time-dependent amplitudes and velocities. Dynamics of l-lump wave and interactions of two lump wave are illustrated. 展开更多
关键词 non-isospectral Kadomtsev-Petviashvili I equation inverse scattering transform lump solutions
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The Crucial Role of Time in M&A Activities: An Inductive Exploration
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作者 Nicole Zadrazil Othmar Lehner Heimo Losbichler 《Journal of Modern Accounting and Auditing》 2017年第8期350-370,共21页
Mergers & acquisitions (M&As) are important strategic instruments, yet nearly half of all transactions fail, often resulting in disastrous write-offs and losses for corporations and financing institutions alike - ... Mergers & acquisitions (M&As) are important strategic instruments, yet nearly half of all transactions fail, often resulting in disastrous write-offs and losses for corporations and financing institutions alike - despite promising prospects upfront. Applied research has been trying to find a "panacea" to prevent or at least predict M&A failure, investigating motives, synergies and performance. Despite the growing unease with the stationary explanatory models in literature, research has only marginally focused on the concept of time, with inquiries into market timing and integration speed. Yet other timing concepts have been neglected in concepts so far despite early empirical evidence for their existence. The purpose of this paper is thus to identify and elaborate on the importance of further relevant theories of timing. For this, and true to the exploratory nature of the topic, the authors have chosen a qualitative comparative case study design based on existing case reports which are investigated for narrations highlighting timing concepts. This study reveals six factors which have a crucial impact on the M&A outcome: time of acquisition, M&A duration in its entirety, M&A sequence, synergy chronology, frequency of acquisitions and time to step back. It contributes to theory and practice in outlining the careful attention that needs to be paid in planning in these factors to enhance the chances of a successful M&A transaction. 展开更多
关键词 M&A SUCCESS timing concepts process SYNERGY
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New Exact Solutions and Dynamics in(3+1)-Dimensional Gross–Pitaevskii Equation with Repulsive Harmonic Potential 被引量:1
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作者 王晓丽 武振华 《Communications in Theoretical Physics》 SCIE CAS CSCD 2014年第5期583-589,共7页
Using an improved homogeneous balance principle and an F-expansion technique, we construct the new exact periodic traveling wave solutions to the(3+1)-dimensional Gross–Pitaevskii equation with repulsive harmonic pot... Using an improved homogeneous balance principle and an F-expansion technique, we construct the new exact periodic traveling wave solutions to the(3+1)-dimensional Gross–Pitaevskii equation with repulsive harmonic potential. In the limit cases, the solitary wave solutions are obtained as well. We also investigate the dynamical evolution of the solitons with a time-dependent complicated potential. 展开更多
关键词 Gross-Pitaevskii equation exact solution solitory wave periodic wave F-expansion
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