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Simulation study on ultrasonic tomography for grouted reinforced concrete by finite element
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作者 朱自强 喻波 +2 位作者 李亚楠 肖嘉莹 周勇 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第7期2791-2799,共9页
A finite element reconstruction algorithm for ultrasound tomography based on the Helmholtz equation in frequency domain is presented to monitor the grouting defects in reinforced concrete structures.In this algorithm,... A finite element reconstruction algorithm for ultrasound tomography based on the Helmholtz equation in frequency domain is presented to monitor the grouting defects in reinforced concrete structures.In this algorithm,a hybrid regularizations-based iterative Newton method is implemented to provide stable inverse solutions.Furthermore,a dual mesh scheme and an adjoint method are adopted to reduce the computation cost and improve the efficiency of reconstruction.Simultaneous reconstruction of both acoustic velocity and attenuation coefficient for a reinforced concrete model is achieved with multiple frequency data.The algorithm is evaluated with numerical simulation under various practical scenarios including varied transmission/receiving modes,different noise levels,different source/detector numbers,and different contrast levels between the heterogeneity and background region.Results obtained suggest that the algorithm is insensitive to noise,and the reconstructions are quantitatively accurate in terms of the location,size and acoustic properties of the target over a range of contrast levels. 展开更多
关键词 ultrasound computed tomography nondestructive testing concrete exact field finite element method
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Three-dimensional velocity structure and tectonic characteristics of earthquake area in Yibin
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作者 Ma Yong Bi Jin-Meng and Gao Lei 《Applied Geophysics》 SCIE CSCD 2019年第3期267-276,394,共11页
In this study,on the basis of absolute first-arrival times of 84756 P-and S-waves from 6085 earthquakes recorded at 56 fixed stations in Yibin and surrounding areas in China from January 2009 to January 2019,focal par... In this study,on the basis of absolute first-arrival times of 84756 P-and S-waves from 6085 earthquakes recorded at 56 fixed stations in Yibin and surrounding areas in China from January 2009 to January 2019,focal parameters and three-dimensional(3 D)body-wave high-resolution velocity structures at depths of 0–30 km were retrieved by double-difference tomography.Results show that there is a good correspondence between the spatial distribution of the relocated earthquakes and velocity structures,which were concentrated mainly in the high-velocity-anomaly region or edge of high-velocity region.Velocity structure of P-and S-waves in the Yibin area clearly shows lateral inhomogeneity.The distribution characteristics of the P-and S-waves near the surface are closely related to the geomorphology and geologic structure.The low-velocity anomaly appears at the depth of 15–25 km,which is affected by the lower crust current.The Junlian–Gongxian and Gongxian–Changning earthquake areas,which are the two most earthquake-prone areas in the Yibin region,clearly differ in earthquake distribution and tectonic characteristics.We analyzed the structural characteristics of the Junlian–Gongxian and Gongxian–Changning earthquake areas on the basis of the 3 D bodywave velocity structures in the Yibin region.We found that although most seismicity in the Yibin area is caused by fluid injection,the spatial position of seismicity is controlled by the velocity structures of the middle and upper crust and local geologic structure.Fine-scale 3 D velocity structures in the Yibin area provide important local reference information for further understanding the crustal medium,seismogenic structure,and seismicity. 展开更多
关键词 Yibin area double-difference tomography method 3D P・wave and S・wave velocity structure structural characteristics
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The Progression of the Impurities Injected into the Plasma Following by Soft X-ray Arrays on HL-2A Tokamak
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作者 DENG Wei LIU Yi DONG Yunbo CUI Zhengying FU Bingzhong ZHANG Peng 《Southwestern Institute of Physics Annual Report》 2005年第1期28-31,共4页
Small amounts of metallic impurity is injected by laser blow-off on HL-2A tokamak in order to study transport phenomena. The particle transport is interpretated along
关键词 Impurity injection tomography method Sawtooth
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Advances in shape measurement in the digital world 被引量:1
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作者 Xiaodong Jia Edward J. Garboczi 《Particuology》 SCIE EI CAS CSCD 2016年第3期19-31,共13页
The importance of particle shape in terms of its effects on the behaviour of powders and other particulate systems has long been recognised, but particle shape information has been rather difficult to obtain and use u... The importance of particle shape in terms of its effects on the behaviour of powders and other particulate systems has long been recognised, but particle shape information has been rather difficult to obtain and use until fairly recently, unlike its better-known counterpart, particle size. However, advances in computing power and 3D image acquisition and analysis techniques have resulted in major progress being made in the measurement, description and application of particle shape information in recent years. Because we are now in a digital era, it is fitting that many of these advanced techniques are based on digital technology. This review article aims to trace the development of these new techniques, highlight their contributions to both academic and practical applications, and present a perspective for future developments. 展开更多
关键词 Particle shape Digital methods Shape measurement Spherical harmonics X-ray tomography
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