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RISS 인기검색어
- 검색키워드
- 저자 : Zhongqing Chen (검색결과 5 건)
- 무료
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Chen, Jiangang,Su, Zhongqing,Cheng, Li Techno-Press 2012 Coupled systems mechanics Vol.1 No.4
As a result of the medium coupling, propagation characteristics of ultrasonic waves guided by a multi-phase medium can be different from those in a homogeneous system. This phenomenon becomes prominent for a medium consisting of phases with considerably distinct material and physical properties (e.g., submerged structures or human bones covered with soft tissues). In this study, the coupling effect arising from both fluid and soft tissues on wave propagation in engineering structures and human bone phantoms, respectively, was explored and calibrated quantitatively, with a purpose of enhancing the precision of ultrasonic-wave-based non-destructive evaluation (NDE) and clinical quantitative ultrasound (QUS). Calibration results were used to rectify conventional NDE during evaluation of corrosion in a submerged aluminium plate, and QUS during prediction of simulated healing status of a mimicked bone fracture. The results demonstrated that with the coupling effect being appropriately taken into account, the precision of NDE and QUS could be improved.
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Exploring and calibrating local curvature effect of cortical bone for quantitative ultrasound (QUS)
Chen, Jiangang,Su, Zhongqing,Cheng, Li,Ta, De-An Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.4
Apart from thinning of cortical layers, the local bone curvature, varying along bone periphery, modulates ultrasound waves as well, which is however often underestimated or overlooked in clinical quantitative ultrasound (QUS). A dedicated three-dimensional finite element modelling technique for cortical bones was established, for quantitatively exploring and calibrating the effect of local curvature of cortical bone on ultrasound. Using a correlation-based mode extraction technique, high-velocity group (HVG) and low-velocity group (LVG) wave modes in a human radius were examined. Experimental verification using acrylic cylinders and in vitro testing using a porcine femur were accomplished. Results coherently unravelled the cortical curvature exerts evident influence on bone-guided ultrasound when RoC/${\lambda}$ <1 for HVG mode and RoC/${\lambda}$ <2 for LVG mode (RoC/${\lambda}$: the ratio of local bone curvature radius to wavelength); the sensitivity of LVG mode to bone curvature is higher than HVG mode. It has also been demonstrated the local group velocity of an HVG or LVG mode at a particular skeletal site is equivalent to the velocity when propagating in a uniform cylinder having an outer radius identical to the radius of curvature at that site. This study provides a rule of thumb to compensate for the effect of bone curvature in QUS.
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Exploring and calibrating local curvature effect of cortical bone for quantitative ultrasound (QUS)
Jiangang Chen,Zhongqing Su,Li Cheng,De-an Ta 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.4
Apart from thinning of cortical layers, the local bone curvature, varying along bone periphery,modulates ultrasound waves as well, which is however often underestimated or overlooked in clinical quantitative ultrasound (QUS). A dedicated three-dimensional finite element modelling technique for cortical bones was established, for quantitatively exploring and calibrating the effect of local curvature of cortical bone on ultrasound. Using a correlation-based mode extraction technique, high-velocity group (HVG) and low-velocity group (LVG) wave modes in a human radius were examined. Experimental verification using acrylic cylinders and in vitro testing using a porcine femur were accomplished. Results coherently unravelled the cortical curvature exerts evident influence on bone-guided ultrasound when RoC/λ<1 for HVG mode and RoC/λ<2 for LVG mode (RoC/λ: the ratio of local bone curvature radius to wavelength); the sensitivity of LVG mode to bone curvature is higher than HVG mode. It has also been demonstrated the local group velocity of an HVG or LVG mode at a particular skeletal site is equivalent to the velocity when propagating in a uniform cylinder having an outer radius identical to the radius of curvature at that site. This study provides a rule of thumb to compensate for the effect of bone curvature in QUS.
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Compression Index versus Natural Water Content Relationships for China's Coastal Soft Clays
Yanbin Gao,Zhongqing Chen,David Airey 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11
A large number of Cc - wn (Cc is the compression index and wn is the natural water content) correlations have been proposed by researchers for different soft clays around the world, but comparisons of these correlations and reasons for differences between them are rarely reported. In this paper the Cc - wn relationships of marine soft clays from eight China’s coastal cities are presented. It is found that the north coast clays have larger slope of the Cc - wn relationships (about 0.02) than the south coast clays (about 0.008). Comparisons with Cc - wn relationships for remoulded clays and structured natural clays reported by other researchers show the importance of accounting for soil structure, and the higher compressibility and higher apparent preconsolidation stresses of the north coast clays, in comparison to the south coast clays, are believed to be associated with chemical bonding and other post-depositional changes. Most of the reported Cc - wn correlations for natural soft clays from around the world have slopes of about 0.011, which are applicable to weakly structured clays. To develop a more widely applicable Cc - wn correlation, the effects of soil structure need to be incorporated.
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Kai Wang,Wuxiong Cao,Zhongqing Su,Pengxiang Wang,Xiongjie Zhang,Lijun Chen,Ruiqi Guan,Ye Lu 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.2
Despite proven effectiveness and accuracy in laboratories, the existing damage assessment based on guided ultrasonic waves (GUWs) or acoustic emission (AE) confronts challenges when extended to real-world structural health monitoring (SHM) for railway tracks. Central to the concerns are the extremely complex signal appearance due to highly dispersive and multimodal wave features, restriction on transducer installations, and severe contaminations of ambient noise. It remains a critical yet unsolved problem along with recent attempts to implement SHM in bourgeoning high-speed railway (HSR). By leveraging authors' continued endeavours, an SHM framework, based on actively generated diffuse ultrasonic waves (DUWs) and a benchmark-free condition contrast algorithm, has been developed and deployed via an all-in-one SHM system. Miniaturized lead zirconate titanate (PZT) wafers are utilized to generate and acquire DUWs in long-range railway tracks. Fatigue cracks in the tracks show unique contact behaviours under different conditions of external loads and further disturb DUW propagation. By contrast DUW propagation traits, fatigue cracks in railway tracks can be characterised quantitatively and the holistic health status of the tracks can be evaluated in a real-time manner. Compared with GUW- or AE-based methods, the DUW-driven inspection philosophy exhibits immunity to ambient noise and measurement uncertainty, less dependence on baseline signals, use of significantly reduced number of transducers, and high robustness in atrocious engineering conditions. Conformance tests are performed on HSR tracks, in which the evolution of fatigue damage is monitored continuously and quantitatively, demonstrating effectiveness, adaptability, reliability and robustness of DUW-driven SHM towards HSR applications.
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