电容层析成像直接三维图像重建技术研究
|
摘要
电容层析成像(Electrical Capacitance Tomography,简称ECT)技术是基于测量电容来获得电介质的介电常数分布的一种非侵入性成像技术。它利用放置在被测管道、容器周围的传感器阵列,获取被测非导电物场在不同观测角度下的投影数据,即电容测量值,用适当的图像重建算法,重建被测物场的介质(介电常数)分布。这门技术具有成本低、响应速度快、易于实现、非侵入测量方式、安全性能好、适用范围广等优点,使其具有广阔的应用前景。
直接三维ECT技术,需要在被测管道上布置多层测量极板,不但测量同层极板对间的电容值,还要测量不同层极板对间的电容值,三维图像直接在图像重建过程中产生,不经过二维断层成像这一有误差的中间环节,可获得更高质量的三维重建图像。具有很大的研究价值。
本文利用有限元仿真软件,进行了大量仿真实验。从直接三维ECT传感器研究和图像重建算法两个方面对电容层析成像直接三维图像重建技术进行了研究。本文提出轴向分四层,每层四个极板,相邻层之间的旋转角度分别是0°和45°的两种16极板直接三维ECT传感器结构。作者从空满管电容值、灵敏度分析和图像重建质量等方面进行比较,确定出较优的传感器结构。
另外,作者提出一种用多元线性回归方法建立正问题模型,用改进的Landweber迭代算法求解逆问题的直接三维ECT图像重建算法。并与LBP算法、Landweber迭代算法进行了比较研究。结果显示,多元线性回归方法建立的ECT正问题模型模化矩阵病态更小,新算法的重建质量也优于LBP算法和Landweber迭代算法。
Electrical Capacitance Tomography (ECT) is a non-destructive imaging technique that aims at visualization of the permittivity distribution of a dielectric object based on the measured capacitance. Through the appropriate image reconstruction algorithm, it seeks to reconstruct the distribution of medium (permittivity) in the measured object field using the measured capacitances, which are obtained from the sensor arrays laid on the measured pipeline or vessel. This technique has the advantages of low in cost, fast in response, easy to implement, non-invasive measurement, safety in performance and wide range in application, so it has wide application prospects.
Direct 3D ECT needs to arrange multi-layer electrodes around the measured pipeline, and measures the capacitances between not only the same layer but also the different layers of electrodes. The 3D images directly generate in the image reconstruction process, not through the two-dimensional tomography with error, 3D reconstruction images of higher quality is obtained . So this technique has great research value.
In this paper, finite element simulation software is used for a large number of simulation experiments. The author studies the direct 3D ECT image reconstruction technique from the direct 3D ECT sensor as well as image reconstruction algorithm. Direct 3D ECT imaging based on 16 electrodes is researched. These electrodes are arranged in four planes. Every four electrodes on each plane are rotated 0(?) or 45(?) with reference to the previous. The author compares the two sensor structures from the capacitance value of the empty and full pipe, sensitive analysis and image reconstruction quality, then determines the optimum sensor structure.
Furthermore, the author presents ECT forward model established by multiple linear regression method, and also uses the improved Landweber iterative algorithm to solve the ECT inverse problem, and compares with LBP and Landweber algorithm on researching. The result shows that the forward problem model established by multiple linear regression method has lighter ill-conditioned modular matrix, and the reconstruction quality obtained by the new algorithm is better than that obtained by LBP algorithm and Landweber iterative algorithm.
直接三维ECT技术,需要在被测管道上布置多层测量极板,不但测量同层极板对间的电容值,还要测量不同层极板对间的电容值,三维图像直接在图像重建过程中产生,不经过二维断层成像这一有误差的中间环节,可获得更高质量的三维重建图像。具有很大的研究价值。
本文利用有限元仿真软件,进行了大量仿真实验。从直接三维ECT传感器研究和图像重建算法两个方面对电容层析成像直接三维图像重建技术进行了研究。本文提出轴向分四层,每层四个极板,相邻层之间的旋转角度分别是0°和45°的两种16极板直接三维ECT传感器结构。作者从空满管电容值、灵敏度分析和图像重建质量等方面进行比较,确定出较优的传感器结构。
另外,作者提出一种用多元线性回归方法建立正问题模型,用改进的Landweber迭代算法求解逆问题的直接三维ECT图像重建算法。并与LBP算法、Landweber迭代算法进行了比较研究。结果显示,多元线性回归方法建立的ECT正问题模型模化矩阵病态更小,新算法的重建质量也优于LBP算法和Landweber迭代算法。
Electrical Capacitance Tomography (ECT) is a non-destructive imaging technique that aims at visualization of the permittivity distribution of a dielectric object based on the measured capacitance. Through the appropriate image reconstruction algorithm, it seeks to reconstruct the distribution of medium (permittivity) in the measured object field using the measured capacitances, which are obtained from the sensor arrays laid on the measured pipeline or vessel. This technique has the advantages of low in cost, fast in response, easy to implement, non-invasive measurement, safety in performance and wide range in application, so it has wide application prospects.
Direct 3D ECT needs to arrange multi-layer electrodes around the measured pipeline, and measures the capacitances between not only the same layer but also the different layers of electrodes. The 3D images directly generate in the image reconstruction process, not through the two-dimensional tomography with error, 3D reconstruction images of higher quality is obtained . So this technique has great research value.
In this paper, finite element simulation software is used for a large number of simulation experiments. The author studies the direct 3D ECT image reconstruction technique from the direct 3D ECT sensor as well as image reconstruction algorithm. Direct 3D ECT imaging based on 16 electrodes is researched. These electrodes are arranged in four planes. Every four electrodes on each plane are rotated 0(?) or 45(?) with reference to the previous. The author compares the two sensor structures from the capacitance value of the empty and full pipe, sensitive analysis and image reconstruction quality, then determines the optimum sensor structure.
Furthermore, the author presents ECT forward model established by multiple linear regression method, and also uses the improved Landweber iterative algorithm to solve the ECT inverse problem, and compares with LBP and Landweber algorithm on researching. The result shows that the forward problem model established by multiple linear regression method has lighter ill-conditioned modular matrix, and the reconstruction quality obtained by the new algorithm is better than that obtained by LBP algorithm and Landweber iterative algorithm.
引文
[1]陈宇.电容层析成像反问题求解及图像重建算法研究:(博士学位论文).哈尔滨:哈尔滨理工大学,2010.
[2]董向元,郭淑青.电容成像技术及其应用.郑州:黄河水利出版社,2008.
[3]高彦丽.电容层析成像技术中影响图像重建质量的因素分析.华东交通大学学报,2009, 26(1): 62~66.
[4] Wajman R, Banasiak R, et al. Spatial imaging with 3D capacitance measurements. Meas.sci.technol, 2006: 2113~2118.
[5] Yang W Q. Design of electrical capacitance tomography sensors. Measurement Science and Technology, 2010,21(4): 3213~3230.
[6] Marashdeh Q, Fan L S, Du B, et al. Electrical capacitance tomography----a perspective. Industrial & Engineering Chemistry Research, 2008,47(10): 3708~3719.
[7] Kimoto A, Nakatani T, Matsuoka Y, et al. Reconstruction of temperature patterns in the cylindrical head model from electrical capacitance tomography. IEEE Transactions on Instrumentation and Measurement, 2005,54(6): 2407~2411.
[8]邵富群,刘晓欢.层析成像法监测粮仓粮食水分分布的仿真研究.东北大学学报,2006,27(2):134~137.
[9] Huang S M, Plaskowski A, et al. Tomographic imaging of industrial process equipment. Techniques and applications, 1989: 173~177.
[10] Xie C G, Plaskowski A, et al. 8-electrode capacitance system for two-component flow identification part 1: Tomographic flow imaging. IEEE Proceedings Pt..A, 1989: 173~183.
[11] Xie C G, Huang S M, et al. Transputer-based electrical capacitance tomography for real-time imaging of oilfield flow pipeline. Tomography Techniques for Process Design and Operation, Southamphton. Computer Mechanics, 1992: 333~346.
[12] Fasching G E, Smith N S. A capacitance system for three-dimensional imaging of a fluidized beds. Rev.Sci.Instrum, 1992: 2243~2251.
[13] Halow J S, Nicoletti P. Observation of fluidized bed coalescence using capacitance imaging. Powder Technology, 1992: 255~277.
[14]王兴,颜华.电容层析成像技术及发展现状.沈阳工业大学学报,2001,23(6):497-500.
[15] Waterfall R C, White N B, et al. Combustion imaging from electrical impedance measurement, Meas. Sci. Technol, 1996,7(3): 369~374.
[16] Yan H, Shao F Q, Xu H, et al. Three-dimensional electrical capacitance tomography sensing fields, Meas. Sci. Technol,1999,10: 717~725.
[17] Warsito W, Fan L S. Neural network based multi-criterion optimization image reconstruction technique for imaging two-and three-phase flow systems using electrical capacitance tomograph, Meas. Sci. Technol, 2001,12: 2198~2210.
[18] Warsito W, Fan L S. ECT imaging of three-phase fluidized bed based on three-phase capacitance model, Chemical Engineering Science.2003,58: 823~832.
[19]王海刚,刘石,姜凡,杨五强.旋风分离器固体颗粒浓度三维电容层析成像分布.工程热物理学报,2006,27(1):177~179.
[20]周磊,刘石.利用电容层析成像监测泥石流.科技传播,2010-7(下):196~198.
[21]周婧博,邢光龙,杨鼎才.改进的ECT成像法在传送带检测上的应用研究.电子测量技术,2011,34(5):45~48.
[22]赵波.电容层析成像技术图像重建算法研究:(硕士学位论文).唐山:河北理工大学,2007.
[23]王海刚,刘石,杨五强.电容层析成像三维成像算法研究与软件设计.仪器仪表学报,2004,25(6):701~704.
[24]赵进创,傅文利等.电容层析成像系统三维图像重建的研究.计算机应用研究,2004:246~247.
[25] Banasiak R, Wajman R, and Sankowski D. Three-dimensional nonlinear inversion of electrical capacitance tomography data using complete sensor model. Progress in Electromagnetics Research, PIER100, 2010: 219~234.
[26] Warsito W, Marashdeh Q, Fan L S. Electrial capacitance volume Topography. IEEE Sensors Journal, 2007, vol.5, no.4: 525~535.
[27] Soleimani M, Wang H G , et al. A comparative study of 3D electrical capacitance tomography. International Journal of Information and Systems Sciences, 2007: 292~306.
[28]陈德运,李谋遵,郑贵滨.电容层析成像传感器有限元分析及参数优化.电子器件,2006,29(2):427~430.
[29]吴新杰,胡晟,付荣荣.基于COMSOL的电容层析成像系统灵敏度场的计算.辽宁大学学报(自然科学版),2011,38(3):193~196.
[30] Warsito W, Marashdeh Q, Fan L. Some comments on‘Spatial imaging with 3D capacitance measurements’. Meas.sci.technol, 2007: 3665~3667.
[31] Lei J, Liu S, Li Z H, et al. An image reconstruction algorithm based on new objective functional for electrical capacitance tomography. Meas.sci.technol, 2008,19: 1~5.
[32]蔡芹,马宁,苏祥芳等.电容层析成像的BP网络重建.武汉大学学报(自然科学版),1997, 43(1):107~112.
[33]卫怀玉,王大伟,陈德运.基于BP网络的电容层析成像图像重建算法.科苑论坛,2006,11(4):1~4.
[34]任丹.电容层析成像系统图像重建算法的研究:(硕士学位论文).大连:大连理工大学,2006.
[35] XIE C G, HUANG S M, HOYLE B S, et al. Electrical capacitance tomography for flow imaging–system model for development of image reconstruction algorithms and design of primary sensors . IEE Proc.G, 1992, 139(1): 89~98.
[36]刘浩洋.电容层析成像系统图像重建算法的分析和比较:(硕士学位论文).哈尔滨:哈尔滨理工大学,2006.
[37]张惠良,荣冈.电容层析成像中图像重建算法评述.仪器仪表学报.2005,26(3):325~330.
[38]杨钢,王玉涛,邵富群.用于ECT图像重建的预处理Landweber迭代算法.东北大学学报,2006,27(9):953~956.
[39]杨钢,王玉涛,邵富群.电容层析成像图像重建中的迭代算法.仪器仪表学报, 2006,27(12): 1591~1594.
[40]董向元,陈琪,李惊涛.基于快速投影LANDWEBER法的电容层析成像图像重建算法研究.中国电机工程学院,2005,25(14):89~92.
[41]王化祥,王超,陈磊.基于Landweber迭代的图像重建算法.信号处理,2000,16(4):354~357.
[42]颜华,张亮.不采用灵敏度矩阵的ECT图像迭代重建.沈阳工业大学学报,2008,30(4), 458~460.
[43]张亮. ECT重建算法研究与系统软件设计:(硕士学位论文).沈阳:沈阳工业大学,2008.
[44]彭黎辉,陆耿,杨五强.电容成像图像重建算法原理及评价.清华大学学报(自然科学版),2004,44(4):478~484.
[45]刘春婷.电容层析成像系统的算法研究:(硕士学位论文).沈阳:沈阳工业大学,2001.
[46]颜华,邵富群,王师.电容层析成像传感器的优化设计.仪器仪表学报,2000,21(2):139~141.
[2]董向元,郭淑青.电容成像技术及其应用.郑州:黄河水利出版社,2008.
[3]高彦丽.电容层析成像技术中影响图像重建质量的因素分析.华东交通大学学报,2009, 26(1): 62~66.
[4] Wajman R, Banasiak R, et al. Spatial imaging with 3D capacitance measurements. Meas.sci.technol, 2006: 2113~2118.
[5] Yang W Q. Design of electrical capacitance tomography sensors. Measurement Science and Technology, 2010,21(4): 3213~3230.
[6] Marashdeh Q, Fan L S, Du B, et al. Electrical capacitance tomography----a perspective. Industrial & Engineering Chemistry Research, 2008,47(10): 3708~3719.
[7] Kimoto A, Nakatani T, Matsuoka Y, et al. Reconstruction of temperature patterns in the cylindrical head model from electrical capacitance tomography. IEEE Transactions on Instrumentation and Measurement, 2005,54(6): 2407~2411.
[8]邵富群,刘晓欢.层析成像法监测粮仓粮食水分分布的仿真研究.东北大学学报,2006,27(2):134~137.
[9] Huang S M, Plaskowski A, et al. Tomographic imaging of industrial process equipment. Techniques and applications, 1989: 173~177.
[10] Xie C G, Plaskowski A, et al. 8-electrode capacitance system for two-component flow identification part 1: Tomographic flow imaging. IEEE Proceedings Pt..A, 1989: 173~183.
[11] Xie C G, Huang S M, et al. Transputer-based electrical capacitance tomography for real-time imaging of oilfield flow pipeline. Tomography Techniques for Process Design and Operation, Southamphton. Computer Mechanics, 1992: 333~346.
[12] Fasching G E, Smith N S. A capacitance system for three-dimensional imaging of a fluidized beds. Rev.Sci.Instrum, 1992: 2243~2251.
[13] Halow J S, Nicoletti P. Observation of fluidized bed coalescence using capacitance imaging. Powder Technology, 1992: 255~277.
[14]王兴,颜华.电容层析成像技术及发展现状.沈阳工业大学学报,2001,23(6):497-500.
[15] Waterfall R C, White N B, et al. Combustion imaging from electrical impedance measurement, Meas. Sci. Technol, 1996,7(3): 369~374.
[16] Yan H, Shao F Q, Xu H, et al. Three-dimensional electrical capacitance tomography sensing fields, Meas. Sci. Technol,1999,10: 717~725.
[17] Warsito W, Fan L S. Neural network based multi-criterion optimization image reconstruction technique for imaging two-and three-phase flow systems using electrical capacitance tomograph, Meas. Sci. Technol, 2001,12: 2198~2210.
[18] Warsito W, Fan L S. ECT imaging of three-phase fluidized bed based on three-phase capacitance model, Chemical Engineering Science.2003,58: 823~832.
[19]王海刚,刘石,姜凡,杨五强.旋风分离器固体颗粒浓度三维电容层析成像分布.工程热物理学报,2006,27(1):177~179.
[20]周磊,刘石.利用电容层析成像监测泥石流.科技传播,2010-7(下):196~198.
[21]周婧博,邢光龙,杨鼎才.改进的ECT成像法在传送带检测上的应用研究.电子测量技术,2011,34(5):45~48.
[22]赵波.电容层析成像技术图像重建算法研究:(硕士学位论文).唐山:河北理工大学,2007.
[23]王海刚,刘石,杨五强.电容层析成像三维成像算法研究与软件设计.仪器仪表学报,2004,25(6):701~704.
[24]赵进创,傅文利等.电容层析成像系统三维图像重建的研究.计算机应用研究,2004:246~247.
[25] Banasiak R, Wajman R, and Sankowski D. Three-dimensional nonlinear inversion of electrical capacitance tomography data using complete sensor model. Progress in Electromagnetics Research, PIER100, 2010: 219~234.
[26] Warsito W, Marashdeh Q, Fan L S. Electrial capacitance volume Topography. IEEE Sensors Journal, 2007, vol.5, no.4: 525~535.
[27] Soleimani M, Wang H G , et al. A comparative study of 3D electrical capacitance tomography. International Journal of Information and Systems Sciences, 2007: 292~306.
[28]陈德运,李谋遵,郑贵滨.电容层析成像传感器有限元分析及参数优化.电子器件,2006,29(2):427~430.
[29]吴新杰,胡晟,付荣荣.基于COMSOL的电容层析成像系统灵敏度场的计算.辽宁大学学报(自然科学版),2011,38(3):193~196.
[30] Warsito W, Marashdeh Q, Fan L. Some comments on‘Spatial imaging with 3D capacitance measurements’. Meas.sci.technol, 2007: 3665~3667.
[31] Lei J, Liu S, Li Z H, et al. An image reconstruction algorithm based on new objective functional for electrical capacitance tomography. Meas.sci.technol, 2008,19: 1~5.
[32]蔡芹,马宁,苏祥芳等.电容层析成像的BP网络重建.武汉大学学报(自然科学版),1997, 43(1):107~112.
[33]卫怀玉,王大伟,陈德运.基于BP网络的电容层析成像图像重建算法.科苑论坛,2006,11(4):1~4.
[34]任丹.电容层析成像系统图像重建算法的研究:(硕士学位论文).大连:大连理工大学,2006.
[35] XIE C G, HUANG S M, HOYLE B S, et al. Electrical capacitance tomography for flow imaging–system model for development of image reconstruction algorithms and design of primary sensors . IEE Proc.G, 1992, 139(1): 89~98.
[36]刘浩洋.电容层析成像系统图像重建算法的分析和比较:(硕士学位论文).哈尔滨:哈尔滨理工大学,2006.
[37]张惠良,荣冈.电容层析成像中图像重建算法评述.仪器仪表学报.2005,26(3):325~330.
[38]杨钢,王玉涛,邵富群.用于ECT图像重建的预处理Landweber迭代算法.东北大学学报,2006,27(9):953~956.
[39]杨钢,王玉涛,邵富群.电容层析成像图像重建中的迭代算法.仪器仪表学报, 2006,27(12): 1591~1594.
[40]董向元,陈琪,李惊涛.基于快速投影LANDWEBER法的电容层析成像图像重建算法研究.中国电机工程学院,2005,25(14):89~92.
[41]王化祥,王超,陈磊.基于Landweber迭代的图像重建算法.信号处理,2000,16(4):354~357.
[42]颜华,张亮.不采用灵敏度矩阵的ECT图像迭代重建.沈阳工业大学学报,2008,30(4), 458~460.
[43]张亮. ECT重建算法研究与系统软件设计:(硕士学位论文).沈阳:沈阳工业大学,2008.
[44]彭黎辉,陆耿,杨五强.电容成像图像重建算法原理及评价.清华大学学报(自然科学版),2004,44(4):478~484.
[45]刘春婷.电容层析成像系统的算法研究:(硕士学位论文).沈阳:沈阳工业大学,2001.
[46]颜华,邵富群,王师.电容层析成像传感器的优化设计.仪器仪表学报,2000,21(2):139~141.