Finite-difference time-domain simulation of GPR data

Chen, H. W.; Huang, Tsung-Sheng

doi:10.3997/2214-4609.201407229

Cited by 8 publications

(8 citation statements)

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“…Currently, there is a set of mathematical methods, which is highly efficient and diverse with regard to the modelling of electromagnetic wave propagation, e.g. the method of moments [6,7], ray delineation method, with spectral or pseudo spectral methods [8][9][10][11][12][13], methods of differential expression resolutions of Maxwell equations such as differences and finite elements method [14][15][16][17][18][19][20][21]. However, the modelling of the propagation in concrete is not possible without the modelling of the permittivity of the concrete.…”

Section: Electromagnetic Wave Propagation Modelsmentioning

confidence: 99%

Application of Jonscher model for the characterization of the dielectric permittivity of concrete

Bourdi¹,

Rhazi²,

Boone³

et al. 2008

J. Phys. D: Appl. Phys.

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The study of electromagnetic waves propagating in concrete is a complex problem. Understanding the phenomenon of interaction between the wave and the matter is related to the knowledge of the variation process of concrete's electromagnetic properties in terms of its physical characteristics. In particular, dielectric permittivity of concrete is affected by moisture content and change in the frequency of the electromagnetic field applied. In this study, we apply the three-parameter Jonscher model (n, χ r , ε ∞) to show the dispersive aspect of the concrete. The validation of this model is carried out through tests on mortar and concrete at the laboratory, on the one hand, and by comparison of the results with data obtained previously by other researchers, on the other hand. The Jonscher model matches very well the experimental measurements of the concrete. At different moisture levels, heterogeneities and porosities, the results obtained are very good. This shows that this model is very effective and very suitable to represent the dielectric properties of concrete.

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Section: Electromagnetic Wave Propagation Modelsmentioning

confidence: 99%

Application of Jonscher model for the characterization of the dielectric permittivity of concrete

Bourdi¹,

Rhazi²,

Boone³

et al. 2008

J. Phys. D: Appl. Phys.

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“…The GPR set of data was first ascertained using the Ground Vision program (MALA program for quick data illustration). As the resolution of GPR profiles can be enhanced by stacking over many traces or using post-processing software to effectively suppress unwanted noise (Chen and Huang, 1998), the complete GPR set of data was analysed using the REFLEX program for post-processing operations. Four processing steps were performed: static corrections for shifting the traces to zero ground level, background removal, gain adjustment in the y direction and band pass filter to remove the low-frequency bias from the traces.…”

Section: Data Processingmentioning

confidence: 99%

Contribution of geophysics to outlining the foundation structure of the Islamic Museum, Cairo, Egypt

Abbas

Kamei

Helal

et al. 2005

Archaeological Prospection

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The Islamic museumwaserectedin1896.The buildingis situatedin theheart of Cairo (capitalof Egypt) and holdsmarvellous Islamic antiquities and priceless ancient hand-writing andrare books.Recently, a restoration scheme has been planned to secure the old building which suffers from weakened foundations.In addition, the wooden roofs will be replaced by concrete ones and an extra floor will be integrated into the building.Unfortunately, the architecture construction charts were neither available nor obtainable.Therefore, the structure of the foundations and the base walls of the building had to be outlined. At the time of construction, three major fundamental wall designs were dominant and were to be considered during the work approach. Ground-penetrating radar (GPR) and dipole^dipole resistivity imaging have been integrated to (define the structure of the foundation walls ofthe building. A Ramac2 system connected to a 500 MHz antenna has been utilized for conducting the GPR survey. In addition, a Terrameter SAS 1000 single channel device has been used for performing the resistivity profiles. At accessible spaces around the building GPR and resistivity profiles were obtained. The GPR analysis has revealed the depth of the foundation walls to be about 0.9 m from the ground surface with a width close to 0.6 m.The wall design is close to a straight wall style.Furthermore, the analysis ofthe dipole^dipole resistivity measurements has matched the geology of the area, where subsoil anomalies may be due to the scattered limestone blocks that occur in the area. Moreover, the foundation walls have resistivity values that fall into the range of fractured limestone or limestone blocks. A step-wise or inclined foundation wall style hasnot beenindicatedthroughtheparallelresistivityprofiles

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“…In general, they can be classified into three approaches: differential equations, integral equations and simplified analytical solutions. The first approach discretizes the volume of the computational space into grids to find approximate numerical solutions of Maxwell’s equations using Finite‐Element Time‐Domain (FETD) (Chen and Huang ; Harutyunyan ; Durand and Slodicka ) or Finite‐Difference Time‐Domain (FDTD) models (Giannopoulos ; Ghasemi and Abrishamian ; Atteia and Hussein ; Warren and Giannopoulos ). However, these models have not been able to properly describe the actual radar data due to inherent discrepancies between the real and conceptualized antenna model configurations.…”

Section: Introductionmentioning

confidence: 99%

Numerical evaluation of a full‐wave antenna model for near‐field applications

Tran

Warren

André

et al. 2012

Near Surface Geophysics

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In this study, we numerically evaluated a full‐wave antenna model for near‐field conditions using a Finite‐Difference Time‐Domain (FDTD) antenna model. The antenna is effectively characterized by a series of source and field points and global reflection/transmission coefficients, which by using analytical solutions of Maxwell’s equations, enable us to significantly reduce computation times compared to numerical approaches. The full‐wave GPR model was calibrated by a series of radar data from numerical measurements performed above an infinite perfect electrical conductor (PEC). The calibration results provided a very good agreement with data from the FDTD antenna model giving a correlation coefficient of 0.9995. The model was subsequently verified by using it to invert responses from the FDTD antenna model to reconstruct the electrical properties of an artificial medium subject to 8 scenarios of layering, thickness and electrical properties. Full‐wave inverse modelling enabled us to very well reproduce the GPR data both in time and frequency domains, resulting in accurate estimations of the dielectric permittivity even with a two‐layered medium with highly contrasting electrical properties. The relative errors of the permittivity estimation were less than 5% for all medium scenarios and antenna heights. Inversion also provided very good estimations of the electrical conductivity when this parameter was relatively high but poor results were obtained for low conductivities. Surface response analysis showed that the model was more sensitive to permittivity than conductivity and more sensitive to high than low conductivities. Our modelling approach shows great potential to apply full‐wave inversion for retrieving the electrical properties of the subsurface from near‐ and far‐field radar measurements.

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Finite-difference time-domain simulation of GPR data

Cited by 8 publications

References 0 publications

Application of Jonscher model for the characterization of the dielectric permittivity of concrete

Application of Jonscher model for the characterization of the dielectric permittivity of concrete

Contribution of geophysics to outlining the foundation structure of the Islamic Museum, Cairo, Egypt

Numerical evaluation of a full‐wave antenna model for near‐field applications

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