混凝土超声层析成像中的塔式算法
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摘要
针对混凝土超声CT层析成像的常规迭代算法ART,提出了分块迭代的塔式ART算法。该方法克服了传统ART算法计算精度不高,异常体周边单元受异常体影响显著等缺点。其基本思想是按分辨率由小到大的顺序将测区进行逐级分块,利用ART迭代算法计算每一级块单元的波速,并将上一级单元的波速当作下一级单元的迭代初始值,通过不断细化块单元,最终达到重建混凝土测区内部结构图像的目的。对比ART算法改进前后数字模拟试验及混凝土试块试验的结果,说明分块迭代的塔式ART算法在混凝土层析成像中,迭代精度得到提高,异常体位置更明显,并减弱了异常体对周边单元的影响。
An improved algebraic reconstruction technique based on block iteration is proposed,which overcomes traditional ART algorithm's disadvantages of dissatisfying computation precision and great effect of the abnormal object on the abnormal area.The main idea of the new algorithm is to divide the meshes into blocks step by step and to compute the wave speed of each block by ART algorithm until each block can not be divided any more.Computer simulation and the concrete model of ultrasonic computerized tomography show that ART algorithm based on block iteration is capable of improving the precision of computation,making the position of the abnormal more apparent and weakening the influence of the abnormal object on the abnormal area.
An improved algebraic reconstruction technique based on block iteration is proposed,which overcomes traditional ART algorithm's disadvantages of dissatisfying computation precision and great effect of the abnormal object on the abnormal area.The main idea of the new algorithm is to divide the meshes into blocks step by step and to compute the wave speed of each block by ART algorithm until each block can not be divided any more.Computer simulation and the concrete model of ultrasonic computerized tomography show that ART algorithm based on block iteration is capable of improving the precision of computation,making the position of the abnormal more apparent and weakening the influence of the abnormal object on the abnormal area.
引文
[1]杨文采.地球物理反演和地震层析成像[M].北京:地质出版社,1989.
[2]Nolet G.地震层析成像及应用[M].北京:学苑出版社,1989.
[3]李珍照.大坝检查监测中的计算机层析成像技术[J].大坝与安全,1997(1):37-43.
[4]赵明阶,徐蓉.超声波CT成像技术及其在大型桥梁基桩无损检测中的应用[J].重庆交通学院学报,2001,20(2):73-77.
[5]张朋,张兆田.几种CT图像重建算法的研究和比较[J].CT理论与应用研究,2001,10(4):4-9.
[6]Mc Gaughey W J.Comparison of ART,SIRT,Least-squares and SVD Two-Dimensional Tomographic Inver-sion of Field Data[C].60th SEG Expanded Abstracts,1990.
[7]吴新璇.混凝土无损检测技术手册[M].北京:人民交通出版社,2003.
[8]Bond L J,Kepler W F,Frangopol D M.Improved As-sessment of Mass Concrete Dams Using Acoustic Travel Time Tomography,Part I-theory[J].Construction and Building Materials,2000,14(3):133-156.
[2]Nolet G.地震层析成像及应用[M].北京:学苑出版社,1989.
[3]李珍照.大坝检查监测中的计算机层析成像技术[J].大坝与安全,1997(1):37-43.
[4]赵明阶,徐蓉.超声波CT成像技术及其在大型桥梁基桩无损检测中的应用[J].重庆交通学院学报,2001,20(2):73-77.
[5]张朋,张兆田.几种CT图像重建算法的研究和比较[J].CT理论与应用研究,2001,10(4):4-9.
[6]Mc Gaughey W J.Comparison of ART,SIRT,Least-squares and SVD Two-Dimensional Tomographic Inver-sion of Field Data[C].60th SEG Expanded Abstracts,1990.
[7]吴新璇.混凝土无损检测技术手册[M].北京:人民交通出版社,2003.
[8]Bond L J,Kepler W F,Frangopol D M.Improved As-sessment of Mass Concrete Dams Using Acoustic Travel Time Tomography,Part I-theory[J].Construction and Building Materials,2000,14(3):133-156.
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