scholarly journals Research of Computed Tomography Inversion Algorithm for Coal Face Based on Ground Penetrating Radar

2013 ◽  
Author(s):  
Feng Yang ◽  
Cui Du ◽  
Meng Peng ◽  
Zequan Feng ◽  
Yangyang Sun ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Ground Penetrating Radar ◽  
Inversion Algorithm ◽  
Coal Face ◽  
Ground Penetrating ◽  
Tomography Inversion

Research of Computed Tomography Inversion Algorithm for Coal Face Based on Ground Penetrating Radar

2013 ◽  
Vol 765-767 ◽  
pp. 2364-2368 ◽  
Author(s):  
Feng Yang ◽  
Cui Du ◽  
Meng Peng ◽  
Ze Quan Feng ◽  
Yang Yang Sun ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Coal Seam ◽  
Simulation Model ◽  
Ground Penetrating Radar ◽  
Least Square ◽  
Mine Safety ◽  
Qr Factorization ◽  
Computational Time ◽  
Inversion Algorithm ◽  
Ground Penetrating

Currently, mine safety is the focal point in mining activity. As a new and advanced approach for geophysical prospecting, the ground penetrating radar (GPR) is used in the mine disaster detection. Aiming to solve the restriction of low resolution and limited depth of the GPR in the deep coal seam detection, the computed tomography (CT) technology is employed for deep disaster detection in this paper. A large number of coal seam digital simulation model, including different internal diseases, are established, and the simulation data are processed by using the Least Square QR-factorization (LSQR) inversion algorithm, which has the good performance in saving computational time and memory space. Additionally, the influences of iteration precision and grid size on the effect of inversion are analyzed. The inversion results show good agreements with simulation model feature configurations, and the diseases objects can be detected.

Ground-penetrating radar tomography for soil-moisture heterogeneity

Geophysics ◽  
2006 ◽  
Vol 71 (1) ◽  
pp. K9-K18 ◽  
Author(s):  
S. Hanafy ◽  
S. A. al Hagrey
Keyword(s):  
Field Experiment ◽  
Water Content ◽  
Ground Penetrating Radar ◽  
Root Zone ◽  
Bulk Water ◽  
Degree Of Saturation ◽  
Inversion Algorithm ◽  
Index Method ◽  
Direct Model ◽  
Ground Penetrating

Many ground-penetrating radar (GPR) studies incorporate tomographic methods that use straight raypaths for direct model reconstruction, which is unrealistic for media with gradually changing petrophysics. Ray-bending algorithms can sometimes lead to unreliable resolution, especially at interfaces of abrupt dielectric changes. We present an improved GPR tomography technique based on a combination of seismic tomographic methods and a finite-difference solution of the eikonal equation. Our inversion algorithm uses velocity gradient zones and bending rays that represent realistic geology in the subsurface. We tested the technique on theoretical and experimental models with anomalous bodies of varying saturations and velocity and applied it to data from a GPR field experiment that analyzed the root zones of trees. Synthetic results showed that the resolution of our technique is better than that of published methods, especially for local anomalies with sharp velocity contacts. Our laboratory experiments consisted of four objects buried in sand with various water saturations. The GPR tomogram could map the objects and determine their degree of saturation. The velocities are compatible with those of the complex refraction index method; their relationship to the water content fits a previously published empirical equation. Our original field experiment around a poplar tree could map the heterogeneous subsurface and distinguish a central low velocity beneath the tree from the peripheral negative anomaly of a refill. This zone reflects the whole root zone and is caused by its bulk water content of both the organic root network and its surrounding soils.

scholarly journals ESTIMATING DIELECTRIC PERMITTIVITY AND ELECTRIC CONDUCTIVITY FROM SIMULATED MULTICHANNEL GPR PULSES USING ACO AND QUASI-NEWTON INVERSION TECHNIQUES

2014 ◽  
Vol 32 (4) ◽  
pp. 595
Author(s):  
Maria Da Graça Gomes ◽  
Roberto Pinto Souto ◽  
Alexandre Sacco de Athayde ◽  
Marco Túllio Menna Barreto de Vilhena ◽  
Adelir José Strieder
Keyword(s):  
Dielectric Permittivity ◽  
Electric Conductivity ◽  
Ground Penetrating Radar ◽  
Random Noise ◽  
Radar Data ◽  
Inversion Algorithm ◽  
Algorithm Performance ◽  
Ground Penetrating ◽  
Inversion Techniques ◽  
Quasi Newton

ABSTRACT. Inversion of synthetic ground-penetrating radar data to estimate both dielectric permittivity (ε) and electric conductivity (σ) properties simultaneouslyis presented in this paper. The synthetic Ground-Penetrating Radar (GPR) data was generated by the propagation of a one-dimensional electromagnetic wave (1-D EMwave) through a given geological model. The simulated EM trace was modeled by Finite Difference Time Domain method (FDTD) for three different frequencies (f):800, 1000 and 1200 MHz. Random noise was also introduced to evaluate inversion algorithm performance. The inversion of GPR data was performed by Ant ColonyOptimization (ACO) and Quasi-Newton (QN) techniques. A modified ACO technique was applied to approximate conductivity for deepest positions, and to increase theaccuracy and convergence along lower positions. The inversion techniques were able to estimate simultaneously the dielectric permittivity and electric conductivity fromsynthetic multi-frequency GPR data. The estimated electrical parameters can be used to derive a set of physical properties and to develop a better understanding of theunderground geological or geotechnical media.Keywords: ground-penetrating radar, inversion of GPR data, Ant Colony Optimization, Quasi-Newton technique. RESUMO. Neste artigo apresenta-se o registro das ondas eletromagnéticas refletidas (dados sintéticos) e o uso deste registro em algoritmos de inversão que procuramestimar simultaneamente as propriedades permissividade elétrica (ε) e condutividade elétrica (σ). Os dados GPR sintéticos foram gerados pela propagação da onda unidimensional através de um determinado modelo geológico. O traço da onda eletromagnética (OEM) simulado foi modelado pelo método das diferenças finitasno domínio do tempo (FDTD) para três diferentes frequências (f): 800, 1000 e 1200 MHz. Os ruídos randômicos foram introduzidos para verificar a performance doalgoritmo de inversão. Os dados de inversão GPR (permissividade dielétrica e condutividade elétrica) foram obtidos pelos métodosAnt Colony Optimization (Otimização da Colônia de Formigas) (ACO) e Quasi-Newton (QN). O método ACO modificado foi aplicado para aproximar a condutividade em posições mais profundas e aumentara precisão e a convergência ao longo da profundidade. Os métodos de inversão foram capazes de estimar simultaneamente duas propriedades do modelo geológico:a permissividade elétrica e a condutividade elétrica para levantamentos georradar multicanais. Os parâmetros elétricos estimados podem ser usados para derivar umconjunto de propriedades físicas e melhorar a compreensão dos meios geológico-geotécnicos em subsolo.Palavras-chave: radar de penetração no solo, inversão de dados GPR, Otimização da Colônia de Formigas, método Quasi-Newton.

scholarly journals Targeted reflection-waveform inversion of experimental ground-penetrating radar data for quantification of oil spills under sea ice

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. WA59-WA70 ◽  
Author(s):  
John H. Bradford ◽  
Esther L. Babcock ◽  
Hans-Peter Marshall ◽  
David F. Dickins
Keyword(s):  
Sea Ice ◽  
Ground Penetrating Radar ◽  
Oil Spills ◽  
Waveform Inversion ◽  
Radar Data ◽  
The Arctic ◽  
Ice Thickness ◽  
Inversion Algorithm ◽  
Control Value ◽  
Ground Penetrating

Rapid spill detection and mapping are needed with increasing levels of oil exploration and production in the Arctic. Previous work has found that ground-penetrating radar (GPR) is effective for qualitative identification of oil spills under, and encapsulated within, sea ice. Quantifying the spill distribution will aid effective spill response. To this end, we have developed a targeted GPR reflection-waveform inversion algorithm to quantify the geometry of oil spills under and within sea ice. With known electric properties of the ice and oil, we have inverted for oil thickness and variations in ice thickness. We have tested the algorithm with data collected during a controlled spill experiment using 500-MHz radar reflection data. The algorithm simultaneously recovered the thickness of a 5-cm-thick oil layer at the base of the ice to within 8% of the control value, estimated the thickness of a 1-cm-thick oil layer encapsulated within the ice to within 30% of the control value, and accurately mapped centimeter-scale variations in ice thickness.

scholarly journals Ground-penetrating-radar reflection attenuation tomography with an adaptive mesh

Geophysics ◽  
2010 ◽  
Vol 75 (4) ◽  
pp. WA251-WA261 ◽  
Author(s):  
Emily A. Hinz ◽  
John H. Bradford
Keyword(s):  
Ground Penetrating Radar ◽  
Fluid Transport ◽  
Computation Time ◽  
Model Space ◽  
Adaptive Mesh ◽  
Adaptive Meshing ◽  
Inversion Algorithm ◽  
Data Set ◽  
Data Limitations ◽  
Ground Penetrating

Ground-penetrating radar (GPR) attenuation-difference analysis can be a useful tool for studying fluid transport in the subsurface. Surface-based reflection attenuation-difference tomography poses a number of challenges that are not faced by crosshole attenuation surveys. We create and analyze a synthetic attenuation-difference GPR data set to determine methods for processing amplitude changes and inverting for conductivity differences from reflection data sets. Instead of using a traditional grid-based inversion, we use a data-driven adaptive-meshing algorithm to alter the model space and to create a more even distribution of resolution. Adaptive meshing provides a method for improving the resolution of the model space while honoring the data limitations and improving the quality of the attenuation difference inversion. Comparing inversions on a conventional rectangular grid with the adaptive mesh, we find that the adaptively meshed model reduces the inversion computation time by an average of 75% with an improvement in the root mean square error of up to 15%. While the sign of the conductivity change is correctly reproduced by the inversion algorithm, the magnitude varies by as much as much as 50% from the true values. Our heterogeneous conductivity model indicates that the attenuation difference inversion algorithm effectively locates conductivity changes, and that surface-based reflection surveys can produce models as accurate as traditional crosshole surveys.

REFLECTION COEFFICIENT OF AN ELECTROMAGNETIC WAVE IN CONDUCTIVE MEDIA

2018 ◽  
pp. 100-106
Author(s):  
M. S. Sudakova ◽  
M. L. Vladov ◽  
M. R. Sadurtdinov
Keyword(s):  
Reflection Coefficient ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Water Contamination ◽  
Survey Design ◽  
Direct And Inverse Problems ◽  
The Difference ◽  
Ground Penetrating ◽  
Ideal Dielectric

Within the ground penetrating radar bandwidth the medium is considered to be an ideal dielectric, which is not always true. Electromagnetic waves reflection coefficient conductivity dependence showed a significant role of the difference in conductivity in reflection strength. It was confirmed by physical modeling. Conductivity of geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground penetrating radar can be used to solve the problem of mapping of halocline or determine water contamination.

Deteksi Bentuk Objek Bawah Tanah Menggunakan Pengolahan Citra B-Scan pada Ground Penetrating Radar (GPR)

2017 ◽  
Vol 3 (1) ◽  
pp. 73-83
Author(s):  
Rahmayati Alindra ◽  
Heroe Wijanto ◽  
Koredianto Usman
Keyword(s):  
Signal Processing ◽  
Ground Penetrating Radar ◽  
Post Processing ◽  
Data Survey ◽  
Ground Penetrating

Ground Penetrating Radar (GPR) adalah salah satu jenis radar yang digunakan untuk menyelidiki kondisi di bawah permukaan tanah tanpa harus menggali dan merusak tanah. Sistem GPR terdiri atas pengirim (transmitter), yaitu antena yang terhubung ke generator sinyal dan bagian penerima (receiver), yaitu antena yang terhubung ke LNA dan ADC yang kemudian terhubung ke unit pengolahan data hasil survey serta display sebagai tampilan output-nya dan post  processing untuk alat bantu mendapatkan informasi mengenai suatu objek. GPR bekerja dengan cara memancarkan gelombang elektromagnetik ke dalam tanah dan menerima sinyal yang dipantulkan oleh objek-objek di bawah permukaan tanah. Sinyal yang diterima kemudian diolah pada bagian signal processing dengan tujuan untuk menghasilkan gambaran kondisi di bawah permukaan tanah yang dapat dengan mudah dibaca dan diinterpretasikan oleh user. Signal processing sendiri terdiri dari beberapa tahap yaitu A-Scan yang meliputi perbaikan sinyal dan pendektesian objek satu dimensi, B-Scan untuk pemrosesan data dua dimensi  dan C-Scan untuk pemrosesan data tiga dimensi. Metode yang digunakan pada pemrosesan B-Scan salah satunya adalah dengan  teknik pemrosesan citra. Dengan pemrosesan citra, data survey B-scan diolah untuk didapatkan informasi mengenai objek. Pada penelitian ini, diterapkan teori gradien garis pada pemrosesan citra B-scan untuk menentukan bentuk dua dimensi dari objek bawah tanah yaitu persegi, segitiga atau lingkaran. 

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