Thanh Duong Nguyen - Academia.edu (original) (raw)

Papers by Thanh Duong Nguyen

Research paper thumbnail of Identification of sub-surface defect parameters in plates using electromagnetic acoustic interaction

International Journal of Applied Electromagnetics and Mechanics, 2010

This paper proposes a method to identify sub-surface defect parameters in plates, using pulse-ech... more This paper proposes a method to identify sub-surface defect parameters in plates, using pulse-echo EMAT modes. First, the proposed method deploys a reduced simulation model to efficiently reduce the computational cost of EMAT forwa rd analysis. Then, an approach of signal processing based on peak values at back-wall echo and POD method applied to extracted feature of EMAT signal are introduced. Finally, inverse analysis based on reduced POD basics is applied for defect parameters identification. Promising experimental result s with high accuracy on both simulation and synthetic measurement data demonstrate the capability and effectiveness of the proposed method. The extension of this method can be applied in pipe inspection for defect characterization.

Research paper thumbnail of Identification of Crack Profiles using Database and Greedy Search Inverse Analysis Arising in Eddy Current Testing

Transactions of the Institute of Systems, Control and Information Engineers, 2010

This paper is concerned with an optimization method to recover crack profiles from measurement si... more This paper is concerned with an optimization method to recover crack profiles from measurement signals obtained by eddy current testing. This inversion technique uses Greedy search algorithm to find the optimum of least-square error between measurement signals and simulation data. In creating simulation data, a database called ECT database is used. This database is constructed as a set of parameters-to-output mapping data, by using hybrid FEM-BEM simulator derived from Maxwell's equations. Numerical experimental results show the effectiveness and feasibility of this method.

Research paper thumbnail of Estimation of shear-velocity profiles using shear source data in marine environment

The Journal of the Acoustical Society of America, 2012

ABSTRACT This paper estimates seabed shear-velocity profiles and their uncertainties using interf... more ABSTRACT This paper estimates seabed shear-velocity profiles and their uncertainties using interface-wave dispersion curves extracted from data generated by a shear source. The data were collected by 4C ocean bottom cable in a testing experiment of a shear source in the North Sea. The shear source generated a seismic signature over a frequency range between 2 and 60 Hz and was polarized in both in-line and cross-line orientation. Low-frequency Scholte- and Love-wave were recorded. Dispersion curves of the Scholte- and Love-wave for the fundamental mode and higher-order modes are extracted by different time-frequency analysis method. Both vertical (SV) and horizontal (SH) polarized shear-velocity profiles are estimated by Scholte- and Love-wave dispersion curves, respectively. Bayesian approach is used for the inversion. Differential evolution (DE) global search algorithm is applied to estimate the most-probable shear-velocity models. Marginal posterior probability profiles are computed by Metropolis-Hastings sampling. The estimated SV- and SH-velocity profiles are compared and the results provide possibility of studying seabed anisotropy. We thank Statoil ASA for permission to publish the data. The work is partly supported by NFR under Grant No. 186923/I30.

Research paper thumbnail of Estimation of seabed shear-wave velocity profiles using shear-wave source data

The Journal of the Acoustical Society of America, 2013

This paper estimates seabed shear-wave velocity profiles and their uncertainties using interface-... more This paper estimates seabed shear-wave velocity profiles and their uncertainties using interface-wave dispersion curves extracted from data generated by a shear-wave source. The shear-wave source generated a seismic signature over a frequency range between 2 and 60 Hz and was polarized in both in-line and cross-line orientations. Low-frequency Scholte- and Love-waves were recorded. Dispersion curves of the Scholte- and Love-waves for the fundamental mode and higher-order modes are extracted by three time-frequency analysis methods. Both the vertically and horizontally polarized shear-wave velocity profiles in the sediment are estimated by the Scholte- and Love-wave dispersion curves, respectively. A Bayesian approach is utilized for the inversion. Differential evolution, a global search algorithm is applied to estimate the most-probable shear-velocity models. Marginal posterior probability profiles are computed by Metropolis-Hastings sampling. The estimated vertically and horizontally polarized shear-wave velocity profiles fit well with the core and in situ measurements.

Research paper thumbnail of Identification of sub-surface defect parameters in plates using electromagnetic acoustic interaction

International Journal of Applied Electromagnetics and Mechanics, 2010

This paper proposes a method to identify sub-surface defect parameters in plates, using pulse-ech... more This paper proposes a method to identify sub-surface defect parameters in plates, using pulse-echo EMAT modes. First, the proposed method deploys a reduced simulation model to efficiently reduce the computational cost of EMAT forwa rd analysis. Then, an approach of signal processing based on peak values at back-wall echo and POD method applied to extracted feature of EMAT signal are introduced. Finally, inverse analysis based on reduced POD basics is applied for defect parameters identification. Promising experimental result s with high accuracy on both simulation and synthetic measurement data demonstrate the capability and effectiveness of the proposed method. The extension of this method can be applied in pipe inspection for defect characterization.

Research paper thumbnail of Identification of Crack Profiles using Database and Greedy Search Inverse Analysis Arising in Eddy Current Testing

Transactions of the Institute of Systems, Control and Information Engineers, 2010

This paper is concerned with an optimization method to recover crack profiles from measurement si... more This paper is concerned with an optimization method to recover crack profiles from measurement signals obtained by eddy current testing. This inversion technique uses Greedy search algorithm to find the optimum of least-square error between measurement signals and simulation data. In creating simulation data, a database called ECT database is used. This database is constructed as a set of parameters-to-output mapping data, by using hybrid FEM-BEM simulator derived from Maxwell's equations. Numerical experimental results show the effectiveness and feasibility of this method.

Research paper thumbnail of Estimation of shear-velocity profiles using shear source data in marine environment

The Journal of the Acoustical Society of America, 2012

ABSTRACT This paper estimates seabed shear-velocity profiles and their uncertainties using interf... more ABSTRACT This paper estimates seabed shear-velocity profiles and their uncertainties using interface-wave dispersion curves extracted from data generated by a shear source. The data were collected by 4C ocean bottom cable in a testing experiment of a shear source in the North Sea. The shear source generated a seismic signature over a frequency range between 2 and 60 Hz and was polarized in both in-line and cross-line orientation. Low-frequency Scholte- and Love-wave were recorded. Dispersion curves of the Scholte- and Love-wave for the fundamental mode and higher-order modes are extracted by different time-frequency analysis method. Both vertical (SV) and horizontal (SH) polarized shear-velocity profiles are estimated by Scholte- and Love-wave dispersion curves, respectively. Bayesian approach is used for the inversion. Differential evolution (DE) global search algorithm is applied to estimate the most-probable shear-velocity models. Marginal posterior probability profiles are computed by Metropolis-Hastings sampling. The estimated SV- and SH-velocity profiles are compared and the results provide possibility of studying seabed anisotropy. We thank Statoil ASA for permission to publish the data. The work is partly supported by NFR under Grant No. 186923/I30.

Research paper thumbnail of Estimation of seabed shear-wave velocity profiles using shear-wave source data

The Journal of the Acoustical Society of America, 2013

This paper estimates seabed shear-wave velocity profiles and their uncertainties using interface-... more This paper estimates seabed shear-wave velocity profiles and their uncertainties using interface-wave dispersion curves extracted from data generated by a shear-wave source. The shear-wave source generated a seismic signature over a frequency range between 2 and 60 Hz and was polarized in both in-line and cross-line orientations. Low-frequency Scholte- and Love-waves were recorded. Dispersion curves of the Scholte- and Love-waves for the fundamental mode and higher-order modes are extracted by three time-frequency analysis methods. Both the vertically and horizontally polarized shear-wave velocity profiles in the sediment are estimated by the Scholte- and Love-wave dispersion curves, respectively. A Bayesian approach is utilized for the inversion. Differential evolution, a global search algorithm is applied to estimate the most-probable shear-velocity models. Marginal posterior probability profiles are computed by Metropolis-Hastings sampling. The estimated vertically and horizontally polarized shear-wave velocity profiles fit well with the core and in situ measurements.