The present study investigates the wavespace of Highly Contrasted Structures(HCS)and Highly Dissipative Structures(HDS)by wave-based models.The Asymptotic Homogenization Method(AHM),exploits the asymptotic Zig-Zag mod...The present study investigates the wavespace of Highly Contrasted Structures(HCS)and Highly Dissipative Structures(HDS)by wave-based models.The Asymptotic Homogenization Method(AHM),exploits the asymptotic Zig-Zag model and homogenization technique to compute the bending wavenumbers via a 6th-order equation.The General Laminate Model(GLM)employs Mindlin’s displacement field to establish displacement-constraint relationships and resolves a quadratic Eigenvalue Problem(EVP)of the dispersion relation.The Wave Finite Element(WFE)scheme formulates the Nonlinear Eigenvalue Problem(NEP)for waves in varying directions and tracks complex wavenumbers using Weighted Wave Assurance Criteria(WWAC).Two approaches are introduced to estimate the Damping Loss Factor(DLF)of HDS,with the average DLF calculated by the modal density at various angles where non-homogeneity is present.Evaluation of robustness and accuracy is made by comparing the wavenumbers and DLF obtained from AHM and GLM with WFE.WFE is finally extended to a sandwich metastructure with a non-homogeneous core,and the Power Input Method(PIM)with Finite Element Method(FEM)data is employed to assess the average DLF,demonstrating an enhanced DLF compared to layered configurations with the same material portion,indicating increased energy dissipation due to the bending-shear coupling effects.展开更多
针对广域电磁法(Wide Field Electromagnetic Method, WFEM)受噪声影响而导致数据质量低与探测效果不理想的问题.本文提出改进蜣螂优化(Improved DBO, IDBO)长短期记忆网络(Long Short Term Memory, LSTM)的广域电磁去噪方法及应用.首先...针对广域电磁法(Wide Field Electromagnetic Method, WFEM)受噪声影响而导致数据质量低与探测效果不理想的问题.本文提出改进蜣螂优化(Improved DBO, IDBO)长短期记忆网络(Long Short Term Memory, LSTM)的广域电磁去噪方法及应用.首先,利用空间金字塔匹配(Spatial Pyramid Matching, SPM)混沌映射、可变螺旋策略、Levy飞行机制、自适应t分布变异扰动策略改进蜣螂优化算法.然后,利用均方差作为IDBO算法的适应度,实现LSTM算法的超参数寻优.最后,将基于IDBO-LSTM的方法应用于广域电磁数据去噪中.实验表明,IDBO的寻优能力明显优于其他智能优化算法,优化后的LSTM算法在广域电磁数据去噪精度上明显地高于概率神经网络和LSTM算法的效果,处理后的广域电磁数据质量得到显著提升,电场曲线形态更为平稳,本文所提方法能为电磁法反演解释提供技术支持.展开更多
高模态密度结构的宽频振动分析问题是声振分析领域内关注的重点问题之一,可实现宽频振动预测的数值分析方法是该领域内重要的研究内容,有效的宽频振动数值分析方法应在低频至高频域可同时提供精准的数值解。然而,由于明显的耗散误差和...高模态密度结构的宽频振动分析问题是声振分析领域内关注的重点问题之一,可实现宽频振动预测的数值分析方法是该领域内重要的研究内容,有效的宽频振动数值分析方法应在低频至高频域可同时提供精准的数值解。然而,由于明显的耗散误差和计算成本过高导致传统有限元方法(traditional finite element method,TFEM)在对高模态密度结构进行宽频振动分析时,难以在高频域提供精准的数值解,致使无法实现有效的宽频振动分析。而小波有限元分析方法(wavelet finite element method,WFEM)在进行结构分析时具有潜在的求解效率优势,并且可大幅度降低耗散误差带来的影响。为此,本文首先构造了基于小波有限元理论进行宽频振动分析时的自耦合算法,并据此介绍了小波有限元方法对高模态密度结构进行宽频振动分析的架构,形成了宽频小波有限元分析方法(wide wavelet finite element method,WWFEM)。随后,采用数值分析研究方法,基于WWFEM对具有解析解的高模态密度薄板结构进行了宽频振动分析。最后,采用实验分析研究方法,预测了高模态密度结构在宽频域内的振动响应。在此基础上,对比分析了小波有限元方法在进行高频振动分析时的收敛性和宽频振动分析的有效性等。可为依据小波有限元分析方法解决圆柱壳、曲壳等高模态密度结构宽频振动分析问题提供理论参考。展开更多
Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagneti...Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagnetic method(WFEM),in which the pseudo-random signal is taken as the transmitter source,can extract high quality resistivity data in areas with sever interference by only measuring the electric field component.We use the WFEM to extract the resistivity information of the Dongguashan mine in southeast China.Compared with the audio magnetotelluric(AMT)method,and the controlled source audio-frequency magnetotelluric(CSAMT) method,the WFEM can obtain data with higher quality and simpler operations.The inversion results indicate that the WFEM can accurately identify the location of the main ore-body,which can be used for deep mine exploration in areas with strong interference.展开更多
基金supported by the Natural Sciences and Engineering Research Council of Canada-Discovery Grant(individual)Program(No.NSEC-DG#355433-2009)funded by the LabEx CeLyA(Centre Lyonnais d’Acoustique,No.ANR-10-LABX-0060)of Universite?de Lyon。
文摘The present study investigates the wavespace of Highly Contrasted Structures(HCS)and Highly Dissipative Structures(HDS)by wave-based models.The Asymptotic Homogenization Method(AHM),exploits the asymptotic Zig-Zag model and homogenization technique to compute the bending wavenumbers via a 6th-order equation.The General Laminate Model(GLM)employs Mindlin’s displacement field to establish displacement-constraint relationships and resolves a quadratic Eigenvalue Problem(EVP)of the dispersion relation.The Wave Finite Element(WFE)scheme formulates the Nonlinear Eigenvalue Problem(NEP)for waves in varying directions and tracks complex wavenumbers using Weighted Wave Assurance Criteria(WWAC).Two approaches are introduced to estimate the Damping Loss Factor(DLF)of HDS,with the average DLF calculated by the modal density at various angles where non-homogeneity is present.Evaluation of robustness and accuracy is made by comparing the wavenumbers and DLF obtained from AHM and GLM with WFE.WFE is finally extended to a sandwich metastructure with a non-homogeneous core,and the Power Input Method(PIM)with Finite Element Method(FEM)data is employed to assess the average DLF,demonstrating an enhanced DLF compared to layered configurations with the same material portion,indicating increased energy dissipation due to the bending-shear coupling effects.
文摘针对广域电磁法(Wide Field Electromagnetic Method, WFEM)受噪声影响而导致数据质量低与探测效果不理想的问题.本文提出改进蜣螂优化(Improved DBO, IDBO)长短期记忆网络(Long Short Term Memory, LSTM)的广域电磁去噪方法及应用.首先,利用空间金字塔匹配(Spatial Pyramid Matching, SPM)混沌映射、可变螺旋策略、Levy飞行机制、自适应t分布变异扰动策略改进蜣螂优化算法.然后,利用均方差作为IDBO算法的适应度,实现LSTM算法的超参数寻优.最后,将基于IDBO-LSTM的方法应用于广域电磁数据去噪中.实验表明,IDBO的寻优能力明显优于其他智能优化算法,优化后的LSTM算法在广域电磁数据去噪精度上明显地高于概率神经网络和LSTM算法的效果,处理后的广域电磁数据质量得到显著提升,电场曲线形态更为平稳,本文所提方法能为电磁法反演解释提供技术支持.
文摘高模态密度结构的宽频振动分析问题是声振分析领域内关注的重点问题之一,可实现宽频振动预测的数值分析方法是该领域内重要的研究内容,有效的宽频振动数值分析方法应在低频至高频域可同时提供精准的数值解。然而,由于明显的耗散误差和计算成本过高导致传统有限元方法(traditional finite element method,TFEM)在对高模态密度结构进行宽频振动分析时,难以在高频域提供精准的数值解,致使无法实现有效的宽频振动分析。而小波有限元分析方法(wavelet finite element method,WFEM)在进行结构分析时具有潜在的求解效率优势,并且可大幅度降低耗散误差带来的影响。为此,本文首先构造了基于小波有限元理论进行宽频振动分析时的自耦合算法,并据此介绍了小波有限元方法对高模态密度结构进行宽频振动分析的架构,形成了宽频小波有限元分析方法(wide wavelet finite element method,WWFEM)。随后,采用数值分析研究方法,基于WWFEM对具有解析解的高模态密度薄板结构进行了宽频振动分析。最后,采用实验分析研究方法,预测了高模态密度结构在宽频域内的振动响应。在此基础上,对比分析了小波有限元方法在进行高频振动分析时的收敛性和宽频振动分析的有效性等。可为依据小波有限元分析方法解决圆柱壳、曲壳等高模态密度结构宽频振动分析问题提供理论参考。
基金Project(2018YFC0807802)supported by the National Key R&D Program of ChinaProject(41874081)supported by the National Natural Science Foundation of China
文摘Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagnetic method(WFEM),in which the pseudo-random signal is taken as the transmitter source,can extract high quality resistivity data in areas with sever interference by only measuring the electric field component.We use the WFEM to extract the resistivity information of the Dongguashan mine in southeast China.Compared with the audio magnetotelluric(AMT)method,and the controlled source audio-frequency magnetotelluric(CSAMT) method,the WFEM can obtain data with higher quality and simpler operations.The inversion results indicate that the WFEM can accurately identify the location of the main ore-body,which can be used for deep mine exploration in areas with strong interference.
