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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/49795


    Title: Improved Synthetic Aperture Focusing Technique by Hilbert-Huang Transform for Imaging Defects Inside a Concrete Structure
    Authors: Tong,JH;Chiu,CL;Wang,CY
    Contributors: 土木工程學系
    Keywords: TRANSIENT ELASTIC-WAVES;EMPIRICAL MODE DECOMPOSITION;FLAW DETECTION;IMPACT-ECHO;CONSTANTS;SYSTEM;CRACKS
    Date: 2010
    Issue Date: 2012-03-27 16:16:59 (UTC+8)
    Publisher: 國立中央大學
    Abstract: A useful nondestructive testing tool for civil engineering should immediately reveal defects inside concrete structures at the construction sites. To date, there are few effective methods to image defects inside concrete structures. In this paper, a new nondestructive testing method using elastic waves for imaging possible defects inside concrete is developed. This method integrates the point-source/point receiver scheme with the synthetic aperture focusing technique (SAFT) to increase functioning depth and enhance received signals. To improve image quality, received signals are processed by Hilbert-Huang transform (HHT) to get time-frequency curves for the SAFT process. Compared with conventional SAFT method processing with time-amplitude signals, this new method is capable of providing a better image of defects not only in the numerical simulation but also in the experimental result. The image can reveal the number of defects and their locations and front-end profiles. The results shown in this paper indicate that this new elastic-wave-based method exhibits high capability in imaging the defects of in situ concrete structures.
    Relation: IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
    Appears in Collections:[Department of Civil Engineering] journal & Dissertation

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