Migration technique based on the time-domain model of the Ground Penetrating Radar

2001 ◽  
Author(s):  
Bart Scheers ◽  
Marc P. J. Acheroy ◽  
Andre Vander Vorst
Keyword(s):  
Time Domain ◽  
Ground Penetrating Radar ◽  
Domain Model ◽  
The Time Domain ◽  
Ground Penetrating ◽  
Migration Technique

Time-domain inversion of GPR data containing attenuation due to conductive losses

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. K103-K109 ◽  
Author(s):  
Qingyun Di ◽  
Meigen Zhang ◽  
Maioyue Wang
Keyword(s):  
Time Domain ◽  
Ground Penetrating Radar ◽  
Seismic Data ◽  
Random Noise ◽  
Synthetic Data ◽  
The Time Domain ◽  
Ground Penetrating ◽  
Domain Inversion ◽  
Inversion Techniques ◽  
And Inversion

Many seismic data processing and inversion techniques have been applied to ground-penetrating radar (GPR) data without including the wave field attenuation caused by conductive ground. Neglecting this attenuation often reduces inversion resolution. This paper introduces a GPR inversion technique that accounts for the effects of attenuation. The inversion is formulated in the time domain with the synthetic GPR waveforms calculated by a finite-element method (FEM). The Jacobian matrix can be computed efficiently with the same FEM forward modeling procedure. Synthetic data tests show that the inversion can generate high-resolution subsurface velocity profiles even with data containing strong random noise. The inversion can resolve small objects not readily visible in the waveforms. Further, the inversion yields a dielectric constant that can help to determine the types of material filling underground cavities.

scholarly journals Comparison of modelled and observed responses of a glacier snowpack to ground-penetrating radar

2003 ◽  
Vol 37 ◽  
pp. 293-297 ◽  
Author(s):  
Jack Kohler ◽  
John C. Moore ◽  
Elisabeth Isaksson
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
Ground Penetrating Radar ◽  
Ice Core ◽  
Reflection Coefficients ◽  
Order Of Magnitude ◽  
The Time Domain ◽  
Ground Penetrating ◽  
Physical And Chemical ◽  
Firn Core

AbstractThe upper 10 m of the firn of a Svalbard glacier is imaged along the centre line using a 500 MHz ground-penetrating radar, and a 10 m firn core taken along the profile. Complex reflection coefficients are calculated from the high-resolution capacitance and conductance measurements made on the snow core. The reflection coefficient depth series is converted to the time domain and convolved with model radar monopulses to synthesize traces that compare well with radar traces recorded near the ice core. Differences are probably due to cm-scale physical and chemical inhomogeneities that are smoothed when imaged by the radar beam, which integrates information over areas that are of the same order of magnitude as the depth to the layer.

Successful Application of Ground-Penetrating Radar for Quality Assurance-Quality Control of New Pavements

2003 ◽  
Vol 1861 (1) ◽  
pp. 86-97 ◽  
Author(s):  
Imad L. Al-Qadi ◽  
Samer Lahouar ◽  
Amara Loulizi
Keyword(s):  
Quality Control ◽  
Quality Assurance ◽  
Ground Penetrating Radar ◽  
Test Section ◽  
Base Layer ◽  
Quality Control Tool ◽  
Granular Base ◽  
The One ◽  
The Time Domain ◽  
Ground Penetrating

The successful application of ground-penetrating radar (GPR) as a quality assurance–quality control tool to measure the layer thicknesses of newly built pavement systems is described. A study was conducted on a newly built test section of Route 288 located near Richmond, Virginia. The test section is a three-lane, 370-m-long flexible pavement system composed of a granular base layer and three different hot-mix asphalt (HMA) lifts. GPR surveys were conducted on each lift of the HMA layers after they were constructed. To estimate the layer thicknesses, GPR data were analyzed by using simplified equations in the time domain. The accuracies of the GPR system results were checked by comparing the thicknesses predicted with the GPR to the thicknesses measured directly from a large number of cores taken from the different HMA lifts. This comparison revealed a mean thickness error of 2.9% for HMA layers ranging in thickness from 100 mm (4 in.) to 250 mm (10 in.). This error is similar to the one obtained from the direct measurement of core thickness.

scholarly journals Study Effect of Objects Orientation in the Mediums On GPR Signal Reflections Using FDTD Simulation

2018 ◽  
Vol 3 (11) ◽  
pp. 73-77
Author(s):  
Aye Mint Mohamed Mostapha ◽  
Gamil Alsharahi ◽  
Abdellah Driouach
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Ground Penetrating Radar ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Ground Surface ◽  
Propagation Path ◽  
Fdtd Simulation ◽  
Ground Penetrating ◽  
Dielectric Objects

Ground penetrating radar (GPR) is a very effective tool for detecting and identifying objects below the ground surface.  based on  the propagation and reflection of high-frequency electromagnetic waves. The GPR reflection can be affected by many things like the type of objects orientation, their shapes ..ect. The purpose of this paper is to  study by simulation the effect of objects orientation in two different mediums (dry and wet sand) on the GPR signal reflection using Reflexw software which is based on a numerical method known as finite difference in time domain (FDTD).  The simulations that have been realized included a conductor  and dielectric objects. The results obtained have led us to find that the propagation path, the reflection strength and the signal form change with the change of object orientation and nature. To confirm the validity of the results, we compared them with experimental results previously published by researchers under the same conditions.

Coupled Time-Domain Hydro-Elastic Simulation for Submerged Floating Tunnel Under Wave Excitations

2021 ◽  
Author(s):  
Chungkuk Jin ◽  
Sung-Jae Kim ◽  
MooHyun Kim
Keyword(s):  
Time Domain ◽  
Domain Model ◽  
Mooring Line ◽  
Wave Forces ◽  
Rod Theory ◽  
Discrete Module ◽  
Simulation Based ◽  
Submerged Floating Tunnel ◽  
The Time Domain ◽  
Elastic Simulation

Abstract We develop a fully-coupled time-domain hydro-elasticity model for the Submerged Floating Tunnel (SFT) based on the Discrete-Module-Beam (DMB) method. Frequency-domain simulation based on 3D potential theory results in multibody’s hydrodynamic coefficients and excitation forces for tunnel sections. Subsequently, we build the time-domain model with the multibody Cummins equation and external stiffness matrix from the Euler-Bernoulli and Saint-Venant torsion theories. We establish the mooring line model with rod theory and couple components with translational springs at their respective connection locations. We then compare the dynamic motions, wave forces, and mooring tensions between the present and Morison-equation-based elastic models under regular wave excitations at different submergence depths. The present model is especially important for the shallowly submerged tunnel in which the Morison model shows exaggerated motions, especially at high-frequency range.

On Vessel Motion Induced Vortex-Induced Vibrations of a Steel Lazy Wave Riser

2021 ◽  
Author(s):  
Decao Yin
Keyword(s):  
Vortex Shedding ◽  
Time Domain ◽  
Oscillatory Flow ◽  
Domain Model ◽  
Time Varying ◽  
Structure Interaction ◽  
Response Characteristics ◽  
Vortex Induced Vibrations ◽  
The Time Domain ◽  
Vessel Motion

Abstract Deepwater steel lazy wave risers (SLWR) subject to vessel motion will be exposed to time-varying oscillatory flow, vortices could be generated and the cyclic vortex shedding force causes the structure vibrate, such fluid-structure interaction is called vortex-induced vibrations (VIV). To investigate VIV on a riser with non-linear structures under vessel motion and oscillatory flows, time domain approaches are needed. In this study, a time-domain approach is used to simulate a full-scale SLWR. Two cases with simplified riser top motions are simulated numerically. By using default input parameters to the time domain approach, the key oscillatory flow induced VIV response characteristics such as response frequency, curvature and displacements are examined and discussed. More accurate VIV prediction could be achieved by using realistic hydrodynamic inputs into the time domain model.

scholarly journals Application of Laplace Domain Waveform Inversion to Cross-Hole Radar Data

2019 ◽  
Vol 11 (16) ◽  
pp. 1839
Author(s):  
Xu Meng ◽  
Sixin Liu ◽  
Yi Xu ◽  
Lei Fu
Keyword(s):  
Time Domain ◽  
Waveform Inversion ◽  
Radar Data ◽  
Dominant Frequency ◽  
Data Set ◽  
Laplace Domain ◽  
Full Waveform ◽  
Highly Nonlinear ◽  
The Time Domain ◽  
Ground Penetrating

Full waveform inversion (FWI) can yield high resolution images and has been applied in Ground Penetrating Radar (GPR) for around 20 years. However, appropriate selection of the initial models is important in FWI because such an inversion is highly nonlinear. The conventional way to obtain the initial models for GPR FWI is ray-based tomogram inversion which suffers from several inherent shortcomings. In this paper, we develop a Laplace domain waveform inversion to obtain initial models for the time domain FWI. The gradient expression of the Laplace domain waveform inversion is deduced via the derivation of a logarithmic object function. Permittivity and conductivity are updated by using the conjugate gradient method. Using synthetic examples, we found that the value of the damping constant in the inversion cannot be too large or too small compared to the dominant frequency of the radar data. The synthetic examples demonstrate that the Laplace domain waveform inversion provide slightly better initial models for the time domain FWI than the ray-based inversion. Finally, we successfully applied the algorithm to one field data set, and the inverted results of the Laplace-based FWI show more details than that of the ray-based FWI.

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