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Modal macro-strain identification from operational macro-strain shape under changing loading conditions 被引量:1
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作者 李舒 徐赵东 +1 位作者 王少杰 吴智深 《Journal of Southeast University(English Edition)》 EI CAS 2016年第2期219-225,共7页
To develop modal macro-strain ( MMS ) identification techniques and improve their applicability in a continuous health monitoring system for civil infrastructures, the concept of operational macro-strain shape (OMS... To develop modal macro-strain ( MMS ) identification techniques and improve their applicability in a continuous health monitoring system for civil infrastructures, the concept of operational macro-strain shape (OMSS) and the corresponding identification method are proposed under unknown ever-changing loading conditions, and the MMS is then obtained. The core of the proposed technique is mainly based on the specific property that the macro-strain transmissibility tends to be independent of external excitations at the poles of the system and converges to a unique value. The proposed method is verified using the experimental data from a three-span continuous beam excited by an impact hammer at different locations. The identified results are also compared with the commonly used methods, such as the peak- picking (PP) method, the stochastic subspace identification (SSI) method, and numerical results, in the case of unknown input forces. Results show that the proposed technique has unique merits in accuracy and robustness due to its combining multiple tests under changing loading conditions, which also reveal the promising application of the distributed strain sensing system in identifying MMS of operational structures, as well as in the structural health monitoring (SHM) field. 展开更多
关键词 macro-stain/distributed strain fiber Bragggrating FBG operational modal analysis OMA operational deflection shape (ODS) TRANSMISSIBILITY
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Seismic attenuation compensation with spectral-shaping regularization
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作者 QiZhen Du WanYu Wang +1 位作者 WenHan Sun Li-Yun Fu 《Earth and Planetary Physics》 EI CSCD 2022年第3期259-274,共16页
Because of the viscoelasticity of the subsurface medium,seismic waves will inherently attenuate during propagation,which lowers the resolution of the acquired seismic records.Inverse-Q filtering,as a typical approach ... Because of the viscoelasticity of the subsurface medium,seismic waves will inherently attenuate during propagation,which lowers the resolution of the acquired seismic records.Inverse-Q filtering,as a typical approach to compensating for seismic attenuation,can efficiently recover high-resolution seismic data from attenuation.Whereas most efforts are focused on compensating for highfrequency energy and improving the stability of amplitude compensation by inverse-Q filtering,low-frequency leakage may occur as the high-frequency component is boosted.In this article,we propose a compensation scheme that promotes the preservation of lowfrequency energy in the seismic data.We constructed an adaptive shaping operator based on spectral-shaping regularization by tailoring the frequency spectra of the seismic data.We then performed inverse-Q filtering in an inversion scheme.This data-driven shaping operator can regularize and balance the spectral-energy distribution for the compensated records and can maintain the low-frequency ratio by constraining the overcompensation for high-frequency energy.Synthetic tests and applications on prestack common-reflectionpoint gathers indicated that the proposed method can preserve the relative energy of low-frequency components while fulfilling stable high-frequency compensation. 展开更多
关键词 seismic attenuation compensation spectral-shaping regularization data-driven shaping operator offset-related inverse-Q filter
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Structural Damage Detection Method Based on Decomposition of the Operating Deflection Shapes 被引量:1
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作者 ZANG Chaoping 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2011年第3期480-486,共7页
Full-field measurement techniques such as the scanning laser Doppler vibrometer (LDV) and the electronic speckle pattern interferometry systems can provide a dense and accurate vibration measurement on structural op... Full-field measurement techniques such as the scanning laser Doppler vibrometer (LDV) and the electronic speckle pattern interferometry systems can provide a dense and accurate vibration measurement on structural operating deflection shape (ODS) on a relatively short period of time.The possibility of structural damage detection and localization using the ODS looks likely more attractive than when using traditional measurement techniques which address only a small number of discrete points.This paper discusses the decomposition method of the structural ODSs in the time history using principal component analysis to provide a novel approach to the structural health monitoring and damage detection.The damage indicator is proposed through comparison of structural singular vectors of the ODS variation matrixes between the healthy and damaged stages.A plate piece with a fix-free configuration is used as an example to demonstrate the effectiveness of the damage detection and localization using the proposed method.The simulation results show that:(1) the dominated principal components and the corresponding singular vectors obtained from the decomposition of the structural ODSs maintain most of all vibration information of the plate,especially in the case of harmonic force excitations that the 1st principal component and its vectors mostly dominated in the system;(2) the damage indicator can apparently flag out the damage localization in the case of the different sinusoidal excitation frequencies that may not be close to any of structural natural frequencies.The successful simulation indicates that the proposed method for structural damage detection is novel and robust.It also indicates the potentially practical applications in industries. 展开更多
关键词 damage detection DECOMPOSITION operating deflection shape (ODS) principal component
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Identification of Internal Damage in Circular Cylinders through Laser Scanning of Vibrating Surfaces
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作者 Yisu Xi Binkai Shi +3 位作者 Wei Xu Jing Ge Huaxin Zhu Dragoslav Sumarac 《Structural Durability & Health Monitoring》 EI 2022年第2期163-177,共15页
With the aid of non-contact measurements of vibrating surfaces through laser scanning,operating deflection shapes(ODSs)with high spatial resolutions can be used to graphically characterize damage in plane structures.A... With the aid of non-contact measurements of vibrating surfaces through laser scanning,operating deflection shapes(ODSs)with high spatial resolutions can be used to graphically characterize damage in plane structures.Although numerous damage identification approaches relying on laser-measured ODSs have been developed for plate-type structures,they cannot be directly applied to circular cylinders due to the gap between equations of motions of plates and circular cylinders.To fill this gap,a novel approach is proposed in this study for damage identification of circular cylinders.Damage-induced discontinuities of the derivatives of ODSs can be used to gra-phically manifest the occurrence of the damage,and characterize the location and size of the damage.The approach is experimentally validated on a specimen of the circular cylinder component,whose out-of-plane ODSs in an inspection region are acquired through laser scanning using a scanning laser vibrometer.The results suggest that the occurrence,location,and size of the internal damage of the circular cylinder can be identified. 展开更多
关键词 Internal damage identification circular cylinder non-contact vibration measurement laser scanning operating deflection shape
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On problem of the determination of operational mode of towed line array with distorted shape
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作者 LI Qihu(Institute of Acoustics, Academia Sinica) 《Chinese Journal of Acoustics》 1990年第2期139-144,共6页
The distortion of the array shape is one of the main factors which result the performance degeneration from the ideal situation of towed line array (TLA). Based on the ordinary array shape distortion, the directivity ... The distortion of the array shape is one of the main factors which result the performance degeneration from the ideal situation of towed line array (TLA). Based on the ordinary array shape distortion, the directivity function of TLA is presented in this paper. An algorithm for precisely determning the coordinates of each element by means of the inverse elliptic function is derived. A fast approximation of recursive formula for solving distorted array shape is given. According to the comparison between ideal directivity and the directivity of distorted array, the criterion for making decision of operational mode of TLA sonar is presented. So that the performance prediction problem in TLA is solved. The results of system simulation in computer show a good agreement with the theoretical analysis. 展开更多
关键词 TLA On problem of the determination of operational mode of towed line array with distorted shape LINE MODE
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Hopf Hypersurfaces in Complex Two-Plane Grassmannians with Generalized Tanaka–Webster D-Parallel Shape Operator
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作者 Hyunjin LEE Eunmi PAK Young Jin SUH 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2017年第1期61-70,共10页
In this paper, we consider a new notion of generalized Tanaka Webster З-parallel shape operator for a real hypersurface in a complex two-plane Grassrnannian and prove a non-existence theorem of a real hypersurface.
关键词 Complex two-plane Grassmannians real hypersurfaces generalized Tanaka-Webster con-nection parallel shape operator З-parallel shape operator
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Generalized Coherent States for Position-Dependent Effective Mass Systems
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作者 Naila Amir Shahid Iqbal 《Communications in Theoretical Physics》 SCIE CAS CSCD 2016年第12期615-620,共6页
A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of th... A generalized scheme for the construction of coherent states in the context of position-dependent effective mass systems has been presented. This formalism is based on the ladder operators and associated algebra of the system which are obtained using the concepts of supersymmetric quantum mechanics and the property of shape invariance. In order to exemplify the general results and to analyze the properties of the coherent states, several examples have been considered. 展开更多
关键词 generalized coherent states supersymmetric quantum mechanics shape invariance ladder operators position-dependent effective mass systems non-linear oscillators Mandel parameter subPoissonian statistics
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