We discuss geophysical applications of enhanced-power ground penetrating radar. Its technical characteristics assure penetration depth and resolution sufficient for probing weak subsurface boundaries, such as buried riverbeds or interfaces between natural and artificial grounds. Examples of deep GPR scans demonstrate weak protracted echo signals originated at smooth permittivity gradients of the subsurface medium. Their quantitative interpretation can be done with the help of time-domain version of coupled WKB approximation.
This article documents the use of portable georadar for measuring the thickness of sea ice.
This device was developed to replace the method for measuring ice thickness by drilling ice
holes. The device based on the use of the LOZA georadar (ground penetrating radar, GPR)
and a specially developed method of field measurements when landing on the studied ice
formations. The study of the thickness and structure of sea ice by radar method is a complex
problem. The salinity of sea ice determines its significant conductivity, which, in turn, causes
a large attenuation of the electromagnetic signal of the georadar. The widespread GPR with
a pulse power of 50–100 W are not applicable for sounding sea ice precisely because of the
large signal attenuation. The LOZA instrument is equipped with a transmitter with a pulse
power of 1 MW. This is, on average, 10,000 times greater than that of “traditional” GPRs.
Multiple measurements of the thickness of ice formations, carried out on the one-year ice of the
eastern shelf of Sakhalin Island during winter expeditions of 2016 and 2019, have shown that
the device can quickly, accurately and with a high spatial resolution measure the thickness of
both flat and highly deformed ice (hummocks, rafted ice, and rubble field) over large areas.
KEYWORDS: Sea ice thickness; ice formations; georadar; GPR.
Deep Penetration Radar. Exploration of Geological Substructures. Experimental...Leonid Krinitsky
When developing the "Loza" deep penetration radar, great efforts were taken to make the device's sounding depth attractive for geologists and geophysicists. Loza’s deep penetration radar has the following characteristics; ultrahigh power, signal energy concentration in the low-frequency spectrum area, large dynamic range of reflected signal recording [1], enabling the GPR to be applied in the exploration of subsurface structures to depths of 100-150 meters in heavy-textured low-resistivity soils and up to 200-300 meters in high-resistivity rocks.
Formation evaluation and well logging are processes used to determine the properties of subsurface reservoirs and identify commercially viable oil and gas fields. Key logging tools developed over time include resistivity logs in the 1920s, dipmeters in the 1940s, gamma ray and neutron logs in the 1940s, sonic logs in the 1950s, density logs in the 1960s, and logging while drilling was introduced, allowing real-time data acquisition. The document provides a historical overview of the development of various openhole well logging tools and techniques.
Induction logging is a method to measure the resistivity or conductivity of geological formations surrounding a borehole. It works by transmitting an alternating current from a coil, which induces eddy currents in the formation. These currents are then detected by a receiver coil to provide measurements of apparent conductivity. Interpretation of induction logs can help determine lithology, fluid saturation, and locate hydrocarbon-bearing zones. The key advantage is that it does not require direct contact with the borehole mud or formations, making it useful for wells drilled with oil-based muds.
This document provides an overview of well logging techniques. It introduces well logging and describes the borehole environment. It then outlines the main types of well logging as electrical, radioactivity, sonic, and miscellaneous. The document focuses on electrical well logging, describing the resistivity, self-potential, and induction methods. For resistivity logging, it explains tools such as normal/lateral logs, micrologs, laterologs, microlaterologs, and proximity logs. It also discusses using resistivity to determine saturation, flushed zones, and mud filtrate invasion profiles.
The document provides an overview of well logging techniques and tools. It discusses the history of well logging beginning in 1912 and describes some common downhole tools used for well logging including gamma ray, spontaneous potential, neutron, density, resistivity, and acoustic logs. It explains what each tool measures and how the data can be used to evaluate properties of the formation like lithology, porosity, fluid content, and structure for purposes like hydrocarbon exploration and reservoir characterization.
This article documents the use of portable georadar for measuring the thickness of sea ice.
This device was developed to replace the method for measuring ice thickness by drilling ice
holes. The device based on the use of the LOZA georadar (ground penetrating radar, GPR)
and a specially developed method of field measurements when landing on the studied ice
formations. The study of the thickness and structure of sea ice by radar method is a complex
problem. The salinity of sea ice determines its significant conductivity, which, in turn, causes
a large attenuation of the electromagnetic signal of the georadar. The widespread GPR with
a pulse power of 50–100 W are not applicable for sounding sea ice precisely because of the
large signal attenuation. The LOZA instrument is equipped with a transmitter with a pulse
power of 1 MW. This is, on average, 10,000 times greater than that of “traditional” GPRs.
Multiple measurements of the thickness of ice formations, carried out on the one-year ice of the
eastern shelf of Sakhalin Island during winter expeditions of 2016 and 2019, have shown that
the device can quickly, accurately and with a high spatial resolution measure the thickness of
both flat and highly deformed ice (hummocks, rafted ice, and rubble field) over large areas.
KEYWORDS: Sea ice thickness; ice formations; georadar; GPR.
Deep Penetration Radar. Exploration of Geological Substructures. Experimental...Leonid Krinitsky
When developing the "Loza" deep penetration radar, great efforts were taken to make the device's sounding depth attractive for geologists and geophysicists. Loza’s deep penetration radar has the following characteristics; ultrahigh power, signal energy concentration in the low-frequency spectrum area, large dynamic range of reflected signal recording [1], enabling the GPR to be applied in the exploration of subsurface structures to depths of 100-150 meters in heavy-textured low-resistivity soils and up to 200-300 meters in high-resistivity rocks.
Formation evaluation and well logging are processes used to determine the properties of subsurface reservoirs and identify commercially viable oil and gas fields. Key logging tools developed over time include resistivity logs in the 1920s, dipmeters in the 1940s, gamma ray and neutron logs in the 1940s, sonic logs in the 1950s, density logs in the 1960s, and logging while drilling was introduced, allowing real-time data acquisition. The document provides a historical overview of the development of various openhole well logging tools and techniques.
Induction logging is a method to measure the resistivity or conductivity of geological formations surrounding a borehole. It works by transmitting an alternating current from a coil, which induces eddy currents in the formation. These currents are then detected by a receiver coil to provide measurements of apparent conductivity. Interpretation of induction logs can help determine lithology, fluid saturation, and locate hydrocarbon-bearing zones. The key advantage is that it does not require direct contact with the borehole mud or formations, making it useful for wells drilled with oil-based muds.
This document provides an overview of well logging techniques. It introduces well logging and describes the borehole environment. It then outlines the main types of well logging as electrical, radioactivity, sonic, and miscellaneous. The document focuses on electrical well logging, describing the resistivity, self-potential, and induction methods. For resistivity logging, it explains tools such as normal/lateral logs, micrologs, laterologs, microlaterologs, and proximity logs. It also discusses using resistivity to determine saturation, flushed zones, and mud filtrate invasion profiles.
The document provides an overview of well logging techniques and tools. It discusses the history of well logging beginning in 1912 and describes some common downhole tools used for well logging including gamma ray, spontaneous potential, neutron, density, resistivity, and acoustic logs. It explains what each tool measures and how the data can be used to evaluate properties of the formation like lithology, porosity, fluid content, and structure for purposes like hydrocarbon exploration and reservoir characterization.
Well logging involves lowering instruments into boreholes to record measurements of the surrounding geological formations. There are two main types: geological logs based on visual inspection of cuttings or cores brought to the surface, and geophysical logs using downhole instruments to measure physical properties like resistivity, acoustic properties, and radioactivity. Well logging is used for oil and gas exploration and production as well as other purposes like groundwater and environmental studies. It provides important information about parameters like porosity, permeability, and fluid content of the formations.
A small presentation about wireline logs, showing their function or the technology that they use.
Ruhr-Universität Bochum, Petroleum Geology II, Winter Semester 2013/2014.
Electrical Properties of Reservoir RocksM.T.H Group
This document discusses electrical resistivity of rock-fluid systems as measured by well logs. It defines resistivity as the ability of a fluid-saturated rock to impede electric current flow. Resistivity is determined by passing a measured current through a rock sample and measuring the required voltage. Resistivity depends on factors like porosity, pore geometry, lithology, cementation, and clay content. The resistivity of various earth materials is provided, from most resistive (rock) to least (salt water). Resistivity is used to determine water saturation and fluid types in formations.
This document provides information about electrical well logging, including spontaneous potential (SP) and resistivity logs. It discusses what well logging is, the process of wireline logging using measurement sondes lowered into boreholes, and some examples of logging tools. It explains that well logs provide continuous in-situ measurements to determine properties like porosity, lithology, and hydrocarbons. Well logging helps interpret drilling data, extrapolate it between boreholes, and design groundwater systems by providing parameters such as permeability, porosity, and fluid movement.
A geomatics approach to the interpretation of Ground Penetrating Radar (GPR)Stuart Glenday
Presentation to Dept. of Geogrpahy, Queen Mary University of London. Use of 3d visualisation and Geomatics techniques to support interpretation of GPR data.
This document discusses resistivity logs and how they are used to analyze borehole formations. Resistivity is measured in ohms per meter and depends on factors like water volume, temperature, and salinity. Resistivity logs can determine hydrocarbon versus water-bearing zones and indicate permeable zones. The Archie equation relates resistivity to water saturation and uses constants determined by rock type. Different resistivity tools like electrode and induction logs measure resistivity at varying depths around the borehole to analyze fluid content and identify zones.
The document discusses the methods for near-surface seismic refraction surveying. It describes typical equipment used including seismographs, sensors, spread cables, and sources. It outlines survey geometry considerations for sensor and source placement. It also details typical recording parameters, the analysis process of picking first breaks and inverting travel time curves, and references additional analysis techniques and software.
The document provides information about resistivity logs including:
1. It discusses factors that affect resistivity like salinity, porosity, lithology, and clay content. It also explains the principles and theoretical considerations of resistivity logs.
2. It describes different resistivity tools like focused devices (Laterolog, Dual Laterolog, Spherically Focused Log) and unfocused devices (Normal Log, Lateral Log). It also discusses micro-resistivity devices.
3. The document discusses log characteristics including depth of investigation, bed resolution, and different scales used in resistivity logs. It explains how resistivity logs can be used for lithology identification, correlation, and permeability determination.
Electrical and electromagnetic prospectingSwaster Xwax
The document discusses induced polarization (IP) methods, including time-domain measurements which measure voltage response over time after current is switched on or off, frequency-domain measurements which inject alternating current at variable frequencies and measure voltage phase shifts to evaluate impedance spectra, and applications for mineral exploration, mining, hydrogeophysics, environmental investigations, engineering projects, groundwater exploration, and mapping contamination.
Well logs can be states as “a recording against depth of any of the characteristics of the rock formations traversed by a measuring apparatus in the well-bore.”
2 d seismic refraction tomography investigation of a sewage treatment siteAlexander Decker
This study used seismic refraction tomography to investigate subsurface layers at a sewage treatment site in Nigeria. Five seismic profiles were collected and analyzed. The results show three layers: an upper undifferentiated overburden layer with velocities from 891-1421 m/s and thicknesses ranging from 18m in the north to 55m in the south; a partially weathered middle layer with velocities from 3010-5129 m/s; and a fresh granite basement layer below with velocities from 5704-7762 m/s. One profile revealed a fracture zone in the basement at 60m depth that could allow sewage to contaminate groundwater if the lagoons are not lined. The study characterized the subsurface
This document provides an overview of well logging concepts and techniques. It discusses key well log formats and presentations, including standard tracks used for depth, resistivity, porosity, and other measurements. Common logs like SP, gamma ray, resistivity, neutron, and density are examined. Signatures indicating lithology, fluid content, and invasion are described. Proper interpretation requires understanding scales, crossovers caused by lithology changes, and matrix effects. An example of logs in a horizontal well is also provided.
This document discusses nuclear logging methods, including gamma ray, density, and neutron logs. It provides background on how these tools work and what formation properties they measure. Gamma ray logs measure natural radioactivity to identify lithology and correlate between wells. Density logs measure bulk density and are used to estimate porosity and identify fluid types. Neutron logs measure hydrogen content to also determine porosity and fluids. The document explains the operating principles, responses, and applications of each nuclear log.
PIPELINE PLANNING WITH AIRBORNE ELECTROMAGNETICSBrett Johnson
This document summarizes the results of a helicopter electromagnetic survey conducted along a 130km pipeline corridor to map subsurface conductivity and aid in pipeline construction planning. The survey identified areas of shallow bedrock that would require blasting versus deeper overburden that could be trenched. Drill holes along the corridor were used to calibrate the electromagnetic conductivity measurements with actual subsurface conditions. A conductivity value of 6mS/m correlated well with a 2m overburden depth, the depth needed for pipeline trenching. The survey effectively mapped subsurface conditions and reduced costs associated with pipeline planning and construction.
Keck ii observations_of_hemispherical_differences_in_h2o2_on_europaSérgio Sacani
This summary analyzes observations from the Keck II telescope that detected varying amounts of hydrogen peroxide on Europa's surface. Observations over four nights found comparable amounts (~0.13%) of H2O2 on the leading hemisphere, lower amounts (~0.04%) on the anti-Jovian and sub-Jovian hemispheres, and almost none on the trailing hemisphere. This suggests the maximum concentration is found on the leading side, with lower amounts elsewhere, requiring revisions to estimates of Europa's total oxidant abundance and delivery to its subsurface ocean.
Ground geophysical surveys use magnetic, electrical, and gravitational measurements to map subsurface rock properties. Magnetics surveys measure the earth's magnetic field and magnetic responses from rocks to map geology and locate magnetic ore bodies. Resistivity and induced polarization (IP) surveys measure electrical properties to detect disseminated sulfides and map stratigraphy. Time-domain electromagnetics (TDEM) uses electromagnetic induction to identify conductive features like ores, groundwater, and permafrost. Geophysical methods provide non-invasive exploration techniques but their results require careful processing and interpretation.
Application Of Resistivity For Groundwater, Hydrogeology and Pollution ResearchOmokpariolaElshalom
It was a group seminar geophysics course presentation in my year 3 of which I was asked to represent the group in giving an oral presentation of how we can apply resistivity in the geophysical investigation of groundwater, pollution ansd hydrogeology.
GPR Probing of Smoothly Layered Subsurface Medium: 3D Analytical ModelLeonid Krinitsky
An analytical approach to GPR probing of a
horizontally layered subsurface medium is developed, based on the coupled-wave WKB approximation. An empirical model of current in dipole transmitter antenna is used.
Geo-radar LOZA and it application for sounding high resistive sections in Sou...Leonid Krinitsky
The LOZA uses for various purposes such as search for hydrogeological objects, paleo- reliefs, kimberlite pipes and fissures, voids in the underlying medium, and geological structures. Some experiments with the DPR were carried out in South Africa in 2018 where traditionally GPR were used only for mine exploration.
Well logging involves lowering instruments into boreholes to record measurements of the surrounding geological formations. There are two main types: geological logs based on visual inspection of cuttings or cores brought to the surface, and geophysical logs using downhole instruments to measure physical properties like resistivity, acoustic properties, and radioactivity. Well logging is used for oil and gas exploration and production as well as other purposes like groundwater and environmental studies. It provides important information about parameters like porosity, permeability, and fluid content of the formations.
A small presentation about wireline logs, showing their function or the technology that they use.
Ruhr-Universität Bochum, Petroleum Geology II, Winter Semester 2013/2014.
Electrical Properties of Reservoir RocksM.T.H Group
This document discusses electrical resistivity of rock-fluid systems as measured by well logs. It defines resistivity as the ability of a fluid-saturated rock to impede electric current flow. Resistivity is determined by passing a measured current through a rock sample and measuring the required voltage. Resistivity depends on factors like porosity, pore geometry, lithology, cementation, and clay content. The resistivity of various earth materials is provided, from most resistive (rock) to least (salt water). Resistivity is used to determine water saturation and fluid types in formations.
This document provides information about electrical well logging, including spontaneous potential (SP) and resistivity logs. It discusses what well logging is, the process of wireline logging using measurement sondes lowered into boreholes, and some examples of logging tools. It explains that well logs provide continuous in-situ measurements to determine properties like porosity, lithology, and hydrocarbons. Well logging helps interpret drilling data, extrapolate it between boreholes, and design groundwater systems by providing parameters such as permeability, porosity, and fluid movement.
A geomatics approach to the interpretation of Ground Penetrating Radar (GPR)Stuart Glenday
Presentation to Dept. of Geogrpahy, Queen Mary University of London. Use of 3d visualisation and Geomatics techniques to support interpretation of GPR data.
This document discusses resistivity logs and how they are used to analyze borehole formations. Resistivity is measured in ohms per meter and depends on factors like water volume, temperature, and salinity. Resistivity logs can determine hydrocarbon versus water-bearing zones and indicate permeable zones. The Archie equation relates resistivity to water saturation and uses constants determined by rock type. Different resistivity tools like electrode and induction logs measure resistivity at varying depths around the borehole to analyze fluid content and identify zones.
The document discusses the methods for near-surface seismic refraction surveying. It describes typical equipment used including seismographs, sensors, spread cables, and sources. It outlines survey geometry considerations for sensor and source placement. It also details typical recording parameters, the analysis process of picking first breaks and inverting travel time curves, and references additional analysis techniques and software.
The document provides information about resistivity logs including:
1. It discusses factors that affect resistivity like salinity, porosity, lithology, and clay content. It also explains the principles and theoretical considerations of resistivity logs.
2. It describes different resistivity tools like focused devices (Laterolog, Dual Laterolog, Spherically Focused Log) and unfocused devices (Normal Log, Lateral Log). It also discusses micro-resistivity devices.
3. The document discusses log characteristics including depth of investigation, bed resolution, and different scales used in resistivity logs. It explains how resistivity logs can be used for lithology identification, correlation, and permeability determination.
Electrical and electromagnetic prospectingSwaster Xwax
The document discusses induced polarization (IP) methods, including time-domain measurements which measure voltage response over time after current is switched on or off, frequency-domain measurements which inject alternating current at variable frequencies and measure voltage phase shifts to evaluate impedance spectra, and applications for mineral exploration, mining, hydrogeophysics, environmental investigations, engineering projects, groundwater exploration, and mapping contamination.
Well logs can be states as “a recording against depth of any of the characteristics of the rock formations traversed by a measuring apparatus in the well-bore.”
2 d seismic refraction tomography investigation of a sewage treatment siteAlexander Decker
This study used seismic refraction tomography to investigate subsurface layers at a sewage treatment site in Nigeria. Five seismic profiles were collected and analyzed. The results show three layers: an upper undifferentiated overburden layer with velocities from 891-1421 m/s and thicknesses ranging from 18m in the north to 55m in the south; a partially weathered middle layer with velocities from 3010-5129 m/s; and a fresh granite basement layer below with velocities from 5704-7762 m/s. One profile revealed a fracture zone in the basement at 60m depth that could allow sewage to contaminate groundwater if the lagoons are not lined. The study characterized the subsurface
This document provides an overview of well logging concepts and techniques. It discusses key well log formats and presentations, including standard tracks used for depth, resistivity, porosity, and other measurements. Common logs like SP, gamma ray, resistivity, neutron, and density are examined. Signatures indicating lithology, fluid content, and invasion are described. Proper interpretation requires understanding scales, crossovers caused by lithology changes, and matrix effects. An example of logs in a horizontal well is also provided.
This document discusses nuclear logging methods, including gamma ray, density, and neutron logs. It provides background on how these tools work and what formation properties they measure. Gamma ray logs measure natural radioactivity to identify lithology and correlate between wells. Density logs measure bulk density and are used to estimate porosity and identify fluid types. Neutron logs measure hydrogen content to also determine porosity and fluids. The document explains the operating principles, responses, and applications of each nuclear log.
PIPELINE PLANNING WITH AIRBORNE ELECTROMAGNETICSBrett Johnson
This document summarizes the results of a helicopter electromagnetic survey conducted along a 130km pipeline corridor to map subsurface conductivity and aid in pipeline construction planning. The survey identified areas of shallow bedrock that would require blasting versus deeper overburden that could be trenched. Drill holes along the corridor were used to calibrate the electromagnetic conductivity measurements with actual subsurface conditions. A conductivity value of 6mS/m correlated well with a 2m overburden depth, the depth needed for pipeline trenching. The survey effectively mapped subsurface conditions and reduced costs associated with pipeline planning and construction.
Keck ii observations_of_hemispherical_differences_in_h2o2_on_europaSérgio Sacani
This summary analyzes observations from the Keck II telescope that detected varying amounts of hydrogen peroxide on Europa's surface. Observations over four nights found comparable amounts (~0.13%) of H2O2 on the leading hemisphere, lower amounts (~0.04%) on the anti-Jovian and sub-Jovian hemispheres, and almost none on the trailing hemisphere. This suggests the maximum concentration is found on the leading side, with lower amounts elsewhere, requiring revisions to estimates of Europa's total oxidant abundance and delivery to its subsurface ocean.
Ground geophysical surveys use magnetic, electrical, and gravitational measurements to map subsurface rock properties. Magnetics surveys measure the earth's magnetic field and magnetic responses from rocks to map geology and locate magnetic ore bodies. Resistivity and induced polarization (IP) surveys measure electrical properties to detect disseminated sulfides and map stratigraphy. Time-domain electromagnetics (TDEM) uses electromagnetic induction to identify conductive features like ores, groundwater, and permafrost. Geophysical methods provide non-invasive exploration techniques but their results require careful processing and interpretation.
Application Of Resistivity For Groundwater, Hydrogeology and Pollution ResearchOmokpariolaElshalom
It was a group seminar geophysics course presentation in my year 3 of which I was asked to represent the group in giving an oral presentation of how we can apply resistivity in the geophysical investigation of groundwater, pollution ansd hydrogeology.
GPR Probing of Smoothly Layered Subsurface Medium: 3D Analytical ModelLeonid Krinitsky
An analytical approach to GPR probing of a
horizontally layered subsurface medium is developed, based on the coupled-wave WKB approximation. An empirical model of current in dipole transmitter antenna is used.
Geo-radar LOZA and it application for sounding high resistive sections in Sou...Leonid Krinitsky
The LOZA uses for various purposes such as search for hydrogeological objects, paleo- reliefs, kimberlite pipes and fissures, voids in the underlying medium, and geological structures. Some experiments with the DPR were carried out in South Africa in 2018 where traditionally GPR were used only for mine exploration.
Exact Analytical Expression for Outgoing Intensity from the Top of the Atmosp...IOSR Journals
This research is a part of the work devoted on the application of analytical Discrete Ordinate (ADO) method to the polarized monochromatic radiative transfer equation undergoing anisotropic scattering with source function matrix in a finite coupled Atmosphere –Ocean media having flat interface boundary conditions involving specular reflection and transmission matrix. Discontinuities in the derivatives of the Stokes vector with respect to the cosine of the polar angle at smooth interface between the two media with different refractive indices (air and water) is tackled by using a suitable quadrature scheme devised earlier. Atmosphere and ocean are assumed to be homogeneous. No stratification is adopted in the two media. Exact expression for the
emergent radiation intensity vector from the top of the atmosphere is derived. Exact expressions for the emergent polarized radiation intensity vector from the air-water interface as well as from any point of the two medium in any direction can also be derived in terms of eigenvectors and eigenvalues.
This study used ground-penetrating radar (GPR) to analyze the Quaternary stratigraphy of a sandy portion of the Marambaia Isthmus in Brazil. Five radar facies were identified in one GPR profile, representing different depositional environments: facies A and A' showed planar reflections indicating a low-energy beach or shore environment; facies B showed sigmoidal reflections indicating transport of shelf sediments during a marine transgression; facies C showed oblique reflections indicating eolian dune deposition during lower sea levels; and facies D showed well-sorted sand grains deposited by reworking. Together, the facies suggest periods of marine transgression and lower sea levels with dune formation, providing information on the
Lateral resolution and lithological interpretation of surface wave profi lingAdam O'Neill
This document summarizes research on using surface wave profiling to characterize near-surface geology. It discusses issues with lateral resolution when imaging subsurface features like sinkholes. Numerical modeling of a sinkhole in buried hard rock shows that wider sinkholes are resolved better than narrow ones. Field data from Western Australia that combines surface wave and electrical resistivity data illustrates improved lithological interpretation when both methods are used. The researchers investigate ways to enhance lateral resolution, such as using non-linear geophone spacing. They also demonstrate data-driven classification of rock types based on resistivity and shear wave velocity measurements.
Crosshole Seismic Reflection: Coal Mine FieldsAli Osman Öncel
The document summarizes research on using crosshole seismic reflection methods for opencast coal exploration. Small explosive charges are used as sources in one borehole, while hydrophones in a nearby borehole record seismic reflections. This provides high-resolution seismic sections between boreholes. Results from two UK coal sites image coal seams and detect small faults not seen with sparser surface exploration methods. While velocity modeling is challenging, the method can locate hazards for excavation and improve reserve estimates compared to traditional borehole spacing.
1) Ground penetrating radar (GPR) is a geophysical method that uses radar pulses and their reflections to image the subsurface. It can detect objects, changes in material, and voids or cracks.
2) GPR transmits electromagnetic waves into the ground that are reflected back to a receiver antenna when they encounter buried objects or boundaries between materials with different electromagnetic properties. The travel time and strength of the reflected signals are used to infer subsurface structures.
3) GPR data can be processed and analyzed to generate 2D profiles and 3D images showing subsurface reflections from buried objects, cracks, voids, and stratigraphic layers to depths ranging from a few centimeters to several meters depending on the antenna frequency and subsurface properties
This document describes a new polarimetric ground penetrating radar (GPR) system and algorithms to reduce noise and recognize buried targets. It includes:
1) A clustered planar array of crossed dipole antennas is used to obtain high resolution 2D images from four polarization channels (xx, yy, xy, yx).
2) A granular noise filter and shape smoothing filter are applied to enhance signal-to-noise ratio and extract the buried object shape from the GPR images.
3) A shape recognition algorithm compares the extracted shape to a reference target to determine if there is a match or mismatch for target identification.
4) Finite-difference time-domain simulations demonstrate the effectiveness of the proposed GPR
Probing the innermost_regions_of_agn_jets_and_their_magnetic_fields_with_radi...Sérgio Sacani
Desde 1974, observações feitas com o chamado Long Baseline Interferometry, ou VLBI, combinaram sinais de um objeto cósmico recebidos em diferentes rádio telescópios espalhados pelo globo para criar uma antena com o tamanho equivalente à maior separação entre elas. Isso fez com que fosse possível fazer imagens com uma nitidez sem precedentes, com uma resolução 1000 vezes melhor do que Hubble consegue na luz visível. Agora, uma equipe internacional de astrônomos quebrou todos os recordes combinando 15 rádio telescópios na Terra e a antena de rádio da missão RadioAstron, da agência espacial russa, na órbita da Terra. O trabalho, liderado pelo Instituto de Astrofísica de Andalucía, o IAA-CSIC, forneceu novas ideias sobre a natureza das galáxias ativas, onde um buraco negro extremamente massivo engole a matéria ao redor enquanto simultaneamente emite um par de jatos de partículas de alta energia e campos magnéticos a velocidades próximas da velocidade da luz.
Observações feitas no comprimento de onda das micro-ondas são essenciais para explorar esses jatos, já que os elétrons de alta energia se movendo em campos magnéticos são mais proficientes em produzir micro-ondas. Mas a maioria das galáxias ativas com jatos brilhantes estão a bilhões de anos-luz de distância da Terra, de modo que esses jatos são minúsculos no céu. Desse modo a alta resolução é essencial para observar esses jatos em ação e então revelar fenômenos como as ondas de choque e a turbulência que controla o quanto de luz é produzida num dado tempo. “Combinando pela primeira vez rádio telescópios na Terra com rádio telescópios no espaço, operando na máxima resolução, tem permitido que a nossa equipe crie uma antena que tem um tamanho equivalente a 8 vezes o diâmetro da Terra, correspondendo a 20 micro arcos de segundo”, disse José L; Gómez, o líder da equipe no Instituto de Astrofísica de Andalucía, IAA-CSIC.
GPR, or ground penetrating radar, is a non-destructive geophysical technique that uses high frequency electromagnetic waves to image the shallow subsurface. It works by transmitting waves into the ground from an antenna and detecting the reflected signals, with the reflection times corresponding to layer depths. GPR can create 2D or 3D images of underground structures based on contrasts in electrical properties like conductivity and dielectric permittivity, which are affected by material and moisture. Common applications include utility detection, archaeology, and mapping stratigraphy, but performance depends on ground conditions.
This course gives keys to understand the SAR image and specificities: geometry, speckle, penetration capabilities, layovers, multipath, dielectric properties.
Advanced modes: polarimetry, interferomety and POLINSAR are also presented.
Paper presented at the First International Congress of Geosciences: Innovatio...Leonid Krinitsky
the use of low-frequency GPR Loza, for prospecting and exploration of mineral resources. Capabilities. Methodology. Examples. Comparison with other methods.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
This document presents a transit time model for short gate length ion-implanted GaAs MESFETs. It develops a 2D analytical model to calculate the potential distribution and electric field in the channel region. Based on this, it derives an expression for transit time by considering the carrier velocity and saturation effects. It also presents an equation for drain current as a function of transit time, doping profile, and other device parameters. Simulation results using MATLAB are shown for Id-Vd characteristics and transit time for different device geometry and material parameters. The model aims to better understand the underlying device physics of optically controlled GaAs MESFETs.
The document discusses advances in SAR interferometry over the past 20 years for measuring millimeter-scale land motion. Key points include:
1) Revisit times have decreased from 35 days with ERS-1 to 12 days with Sentinel-1 constellations, improving ground motion recovery.
2) Persistent scatterer interferometry techniques like SqueeSAR can now measure motions to the millimeter by using all available interferograms.
3) Atmospheric phase screens still limit accuracy but can be estimated and removed using numerical weather models, GPS, and other independent datasets.
4) Future opportunities include using wide Doppler bandwidths from satellites to achieve high-resolution azimuth measurements of ground motion.
GPS measurements are affected by random and systematic errors that impact accuracy. Errors originate from satellites, signal propagation through the atmosphere, and receivers. Satellite errors include orbital inaccuracies and clock errors. Signals pass through the ionosphere, a dispersive layer, causing refraction dependent on frequency. Receivers have clock errors. Combining dual-frequency measurements eliminates ionospheric delay, the main source of error.
Quantum Current in Graphene Nano Scrolls Based Transistortheijes
Graphene based material application as a new centuery material are growing rappidly its carrier transport phenomenon with fast mobility have been focused resently. In the graphene family nanoscrolls because of their especial structure need to be explored. In the presented work a theoretical model for carrier transport in the arcemedus graphene nanoscrolls is reported. Graphene nanoscroll chairal dependent electrical property is considered and then schottky transistor based platform is modeled. The transport coeficient as a fundamental transport factor is discussed. The geometrical paprameter effect on the working phenomenon is considered as well.
Cavities detection with ground penetrating radar in limestone dominated rock ...Firman Syaifuddin
As one of geophysical method ground penetrating radar uses electromagnetic wave propagation to detecting the anomaly object, the strong relationship between the physical properties of geological material and their electromagnetic properties enable to identification of physical structures in the sub surface. Cavities in limestone dominated rock formation sometimes made problem when construction build above in this area, as prevention to the damage affected by cavities, before construction starting to build we have to identified the possible cave location to preparing special treatment to minimize the risk. Present of cavities give electromagnetic anomaly event and the reflection signal representing changing of electrical properties when we use ground penetrating radar. We applied attributes extraction adopted from seismic method to extracting information about cavities. We use sweetness attribute extraction to identified present of cavities in limestone dominated rock formation
Invited Seminar presented at the VIA Forum Astroparticle Physics Forum COSMOVIA
21 March 2020
http://viavca.in2p3.fr/2010c_o_s_m_o_v_i_a__forum_sd24fsdf4zerfzef4ze5f4dsq34sdteerui45788789745rt7yr68t4y54865h45g4hfg56h45df4h86d48h48t7uertujirjtiorjhuiofgrdsqgxcvfghfg5h40yhuyir/viewtopic.php?f=73&t=3705&sid=c56cbf76f87536fc4c3ff216d9edaba2
Author: O.M. Lecian
Speaker: O.M. Lecian
Abstract: The LHAASO experiment is aimed at detecting highly-energetic particles of cosmological origin within a large
range of energies.
The sensitivity of the experimental apparatus can within the frameworks of statistical fluctuations of the
background.
Acceleration and lower-energy particles can be analyzed.
The anisotropy mass composition of cosmic rays can analytically described.
The LHAASO Experiment is also suited for detecting particles of cosmological origin originated from the breach
(and/or other kinds of modifications) of particle theories paradigms comprehending other symmetry groups.
Some physical implications of anisotropies can be looked for.
The study of anisotropy distribution for particles of cosmological origin as well as the anisotropies of their velocities
both in the case of a flat Minkowskian background as well as in the case of curved space-time can be investigated,
as far as the theoretical description of the cross-section is concerned, as well as for the theoretical expressions of
such quantities to be analyzed.
The case of a geometrical phase of particles can be schematized by means of a geometrical factor.
Particular solutions are found under suitable approximations.
A comparison with the study of ellipsoidal galaxies is achieved.
The case of particles with anisotropies in velocities falling off faster than dark matter (DM) is compared.
The study of possible anisotropies in the spatial distribution of cosmological particles can therefore be described
also deriving form the interaction of cosmic particles with the gravitational field, arising at quantum distances, at
the semiclassical level and at the classical scales, within the framework of the proper description of particles
anisotropies properties.
Ground Penetrating Radar (GPR) has the ability to map subsurface geological structures and detect variations in moisture that could help understand geothermal exploration. However, GPR is limited to shallow depths of less than 50 meters, where most geothermal reservoirs are located. This study uses GPR data from Beijing to create digital models of the subsurface and identify potential geothermal indicators like quartz sinters. The results demonstrate GPR's capability to detect geochemical markers associated with geothermal activity and map prospective geothermal reservoir locations. While GPR has limitations for deep exploration, it shows potential as a new efficient tool for initial geothermal prospecting.
Similar to Deep Penetration Radar: Hydrogeology and Paleorelief of Underlying Medium (20)
Geophysical mapping of the old granite quarry.
The granite quarry was developed by hand in the 17th and 18th centuries, convicts worked in the quarry, and the quarried stone was used for road construction.
Determination of the roof of granites. Determining the depth of the quarry. Determination of the contours of the quarry. Determination of the thickness of bulk soils. Research tool GPR Loza-N, dipole antennas 100 MHz.
GPR survey of the bottom of Lake Chebarkul. Six years after the fall of the C...Leonid Krinitsky
GPR survey at the site of the fall of the Chelyabinsk meteorite, Lake Chebarkul, Chelyabinsk, Russia.
Studying the place of the fall of the Chelyabinsk meteorite in the winter of 2013, GPR-team returned to this place after 6 years.
Numerical studies of the radiation patterns of resistively loaded dipolesLeonid Krinitsky
This document describes a numerical study of the radiation patterns of resistively loaded dipole antennas. It computes the far field radiation patterns as a superposition of transient solutions for infinitesimal dipole elements. The current excitation for each dipole element is modeled as a half cycle of a sine squared waveform that propagates along the antenna at an adjustable speed. The radiation patterns are presented for different dielectric media to model antennas used in ground penetrating radar applications in various materials like water, ice, and soil. Comparisons are made to field observations.
GPR INVESTIGATION es una empresa dedicada a la prospección geofísica geológica exploración y estudio del subsuelo con tecnología rusa de última generación, mediante metodología de Georadar (GPR – Radar de Penetración Terrestre) NO INVASIVA y AMIGABLE con el medio ambiente.
Equipo basado en un método innovador en la geofísica cerca de la superficie.
La principal característica distintiva del GPR Loza es la acumulación de energía en un único impulso de alta tensión transmitido en vez de la síntesis de la señal recibida mediante el procesamiento estroboscópico repetitivo.
El documento describe varias secciones de terreno entre puntos A-F, A-B, C-D y C-G. En cada sección se mencionan características geológicas como material sedimentario, roca madre, fallas, fracturas, agua, nivel del mar y flujo de agua, así como también se nombran algunos pozos de monitoreo designados como pz-06, pz-07 y pz-10.
Georadar survey of the fall of the METEORITE fragment СhebarculLeonid Krinitsky
1. Georadar surveys of Lake Chebarkul in Russia were conducted to locate fragments of the Chelyabinsk meteorite that witnesses reported falling into the lake.
2. The surveys identified an anomaly on the lake bottom with a sharp drop in topography and disruption of the ice layer, which is interpreted as the impact crater from a meteorite fragment.
3. Further evidence supporting the meteorite impact hypothesis includes the meteorite's trajectory approaching the lake from the northeast and ejection of ice around the impact site.
Embracing Deep Variability For Reproducibility and Replicability
Abstract: Reproducibility (aka determinism in some cases) constitutes a fundamental aspect in various fields of computer science, such as floating-point computations in numerical analysis and simulation, concurrency models in parallelism, reproducible builds for third parties integration and packaging, and containerization for execution environments. These concepts, while pervasive across diverse concerns, often exhibit intricate inter-dependencies, making it challenging to achieve a comprehensive understanding. In this short and vision paper we delve into the application of software engineering techniques, specifically variability management, to systematically identify and explicit points of variability that may give rise to reproducibility issues (eg language, libraries, compiler, virtual machine, OS, environment variables, etc). The primary objectives are: i) gaining insights into the variability layers and their possible interactions, ii) capturing and documenting configurations for the sake of reproducibility, and iii) exploring diverse configurations to replicate, and hence validate and ensure the robustness of results. By adopting these methodologies, we aim to address the complexities associated with reproducibility and replicability in modern software systems and environments, facilitating a more comprehensive and nuanced perspective on these critical aspects.
https://hal.science/hal-04582287
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptxshubhijain836
Centrifugation is a powerful technique used in laboratories to separate components of a heterogeneous mixture based on their density. This process utilizes centrifugal force to rapidly spin samples, causing denser particles to migrate outward more quickly than lighter ones. As a result, distinct layers form within the sample tube, allowing for easy isolation and purification of target substances.
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...Creative-Biolabs
Neutralizing antibodies, pivotal in immune defense, specifically bind and inhibit viral pathogens, thereby playing a crucial role in protecting against and mitigating infectious diseases. In this slide, we will introduce what antibodies and neutralizing antibodies are, the production and regulation of neutralizing antibodies, their mechanisms of action, classification and applications, as well as the challenges they face.
PPT on Alternate Wetting and Drying presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Compositions of iron-meteorite parent bodies constrainthe structure of the pr...Sérgio Sacani
Magmatic iron-meteorite parent bodies are the earliest planetesimals in the Solar System,and they preserve information about conditions and planet-forming processes in thesolar nebula. In this study, we include comprehensive elemental compositions andfractional-crystallization modeling for iron meteorites from the cores of five differenti-ated asteroids from the inner Solar System. Together with previous results of metalliccores from the outer Solar System, we conclude that asteroidal cores from the outerSolar System have smaller sizes, elevated siderophile-element abundances, and simplercrystallization processes than those from the inner Solar System. These differences arerelated to the formation locations of the parent asteroids because the solar protoplane-tary disk varied in redox conditions, elemental distributions, and dynamics at differentheliocentric distances. Using highly siderophile-element data from iron meteorites, wereconstruct the distribution of calcium-aluminum-rich inclusions (CAIs) across theprotoplanetary disk within the first million years of Solar-System history. CAIs, the firstsolids to condense in the Solar System, formed close to the Sun. They were, however,concentrated within the outer disk and depleted within the inner disk. Future modelsof the structure and evolution of the protoplanetary disk should account for this dis-tribution pattern of CAIs.
Deep Penetration Radar: Hydrogeology and Paleorelief of Underlying Medium
1. Deep Penetration Radar: Hydrogeology and
Paleorelief of Underlying Medium
V.V. Kopeikin , P.A. Morozov, A.V. Popov,
I.V. Prokopovich
Radio Wave Propagation Department
Pushkov Institute of Terrestrial Magnetism, Ionosphere and
Radio Wave Propagation
108840 Moscow, Troitsk, Russia
prokop@izmiran.ru
A.I. Berkut, L.M. Krinitsky
JSC Company VNIISMI
16 Olimpijskij prospect
129090 Moscow, Russia
lozaberk@yandex.ru
Abstract—We discuss geophysical applications of enhanced-
power ground penetrating radar. Its technical characteristics assure
penetration depth and resolution sufficient for probing weak
subsurface boundaries, such as buried riverbeds or interfaces
between natural and artificial grounds. Examples of deep GPR scans
demonstrate weak protracted echo signals originated at smooth
permittivity gradients of the subsurface medium. Their quantitative
interpretation can be done with the help of time-domain version of
coupled WKB approximation.
Keywords—deep penetration radar, paleorelief, coupled-WKB
approximation
I. INTRODUCTION
Distinctive features of LOZA deep penetration radar
(DPR): enhanced pulse power, signal energy concentration in
the low part of the frequency band, large dynamic range of
registered echo signals [1-2] assure the possibility to study
subsurface media and structures previously not accessible to
ground penetrating radar. The use of DPR makes it possible to
reach large probing depths in wet soils and to resolve low-
contrast geological boundaries. These capabilities meet a wide
demand in the field of non-invasive studies of the
hydrogeological structure and paleorelief of the underlying
medium.
Main technical characteristics of standard Loza-N DPR
[2]:
1. Receiver frequency band: 1-50 MHz.
2. Antennas: resistively loaded half-wavelength dipoles of
Wu-King type, central frequencies from 25 MHz (6 meter)
to 50 MHz (3 meter long).
3. Transmitter voltage supplied to antenna: 10 and 21 kV.
4. Pulse repetition rate: 150-200 s-1
.
5. Radar potential (max transmitted over min received
signal): not less than 120 dB.
In the next Section, examples of deep probing data
obtained with Loza-N DPR are given. Looking somewhat
different from commonly accepted GPR data appearance, they
require a short introductory explanation.
The amplitude and phase values on the radargrams are
expressed in a color palette. By convention, it is accepted that
the “positive” amplitude values are displayed by different
hues of red while the “negative” ones – with different tones
of blue to dark blue. All the recorded values of the return
signal amplitude are depicted in a 256-level color palette,
with the least amplitude levels corresponding to yellow tones.
The variations of the pseudocolor on a radargrams make it
possible to visually represent the entire dynamic range of the
amplitudes (more than 120 dB) and the sign of the reflected
signal. One has to keep in mind that the geophysical meaning
have only the shape of the boundaries between different color
zones and the order of color variations.
The set of colors and the shape of the between different
color zones represent the radar image of the geological
structure obtained with the help of the electromagnetic
probing signal [3]. In order to distinguish weak signals and
visualize low-contrast interfaces we apply so called
“amplitude selection” method. By means of this algorithm it
is possible to replace the selected hue (for example, one of
10-15 tones of red, difficult distinguishable by the eye), with
a contrast color, for example, black. This replacement will be
done automatically on the whole radar scan and the new
contrast tone will emphasize the chosen amplitude value. As
a result, the selected amplitude will visually represent the fine
structure of the reflected signal variations.
II. EXAMPLES OF DEEP GPR PROBING
Consider two practical examples of deep probing data
obtained with Loza-N DPR. Both are concerned with the
problem of paleorelief recovering (former riverbeds, etc.). The
first data set was obtained in the Black Sea coastal zone near
Odessa. An aerial photograph of the survey zone and the
starting point of the GPR scan are shown in Fig. 1 (a-b). Figure
1 (c). presents a series of GPR return signals (B-scan) taken
along the survey path, marked with red arrow, across the
natural sand bridge separating the Odessa Gulf from the salty
estuary of Kuyalnik. Below, three individual wave forms (A-
scans) selected at characteristic points of the profile are
shown. In the middle part of the scan a massive alien object is
Supported in part by RFBR grant No. 18-02-00185.
2. clearly seen (the red spot between 40 and 120 meter marks).
Its structure reveals a buried element of the paleorelief – the
former riverbed corresponding to the zone where a protracted
low-frequency signal of positive polarization is recorded (see
A-scan 2 at the 90th meter mark). Outside this zone, a negative
low-frequency signal is recorded at the same depths – see
waveforms 1 and 3 (10th and 180th meter marks). Such a
difference in the reflected signal waveforms indicates
different vertical distribution of the water- and salt content in
the soil. It was shown in [2] (see also Section III of this paper)
(a) (b)
Fig. 2. (a) Rubble dam closing a ravine to
make an industrial pond. (b) Top: B-scan
over the dam, starting from bedrocks (0-
200 m) and crossing the ravine (250-500
m); Bottom: selected A-scans 4-6.
5 64
(a)
(b)
(c)
3. that the waveform 2, characteristic for the middle part of the
B-scan, corresponds to a smooth increase of the soil
permittivity ( )z and conductivity ( )z which can be
explained by the increasing content of salty water. The
boundary of the higher permittivity zone reflects the shape of
the buried riverbed.
A similar pattern can be seen in the B-scan taken along the
dam of an industrial pond near Ufa, Russian Federation – see
Fig 2 (a). Up to the 220 meter mark (the left part of the picture)
The GPR path passed over the natural ground forming the
pond waterside. From 220-250 meter marks, the survey was
led along the dam blocking a ravine in order to close the pond.
The height (actually, the depth) of the dam is about 15 meters.
An alien object is clearly seen in the GPR B-scan as a contrast
red spot extended from 250th to 500th meter mark. Its shape
characterizes the bulk of the dam. The contour of the paleo-
riverbed (the ravine bottom) is marked by the transition from
red to green colors, caused by a fast attenuation of the
reflected signal – see waveforms 5-6). The contrast signal
behavior is evidently corresponding to the electrical properties
difference between primary and filled-up grounds. As we can
see, the artificial ground has a higher permittivity, which can
be explained by the enhanced water content, compared with
the bedrock.
III. MODELING AND RECONSTRUCTION OF SUBSURFACE
RELIEF
Geophysicists working with Loza-N DPR equipment have
gained a vast experience in the comparative analysis of low-
frequency GPR data and the results of geological drilling [10].
Their interpretation skill makes it possible to accurately select,
by means of GPR data, the zones of varying dielectric
permittivity ( )z or enhanced conductivity ( )z and relate
them with certain geological structures. The distant theory
objective is to replace the empirical approach with a reliable
solution of a well-posed inverse problem. However, full-wave
inversion of GPR data presents a serious mathematical and
computational problem, is extremely time-consuming and
generally not having a unique solution [3-5]. In this situation,
physics-based simplified subsurface sounding models and
approximate solutions of the inverse problem always are
wanted by practical geophysicists. In this respect, the quasi-
1D theory of cumulative subsurface reflections developed in
our works [6-7] may present a good palliative.
A qualitative assessment of deep GPR echoes from
smooth subsurface medium gradients is based on the time-
domain version of coupled-WKB approximation [8-9]. By
transforming the classical Bremmer-Brekhovskikh solution
into time domain we obtain a closed-form description of the
radar return signal ( )g s produced by partial reflections of the
initial EM pulse ( )f s from the gradually varying dielectric
permittivity profile ( )z [6]:
( )
0 0
1 ( )
( ) [ 2 ( ) ] .
4 ( )
Z s z
z
g s f s d dz
z
(1)
This formula has an evident physical meaning: the initial pulse
travels from the earth surface 0z , according to the laws of
geometrical optics, towards the virtual reflection level z ,
(a) (b) (c)
(d) (e) (f)
Fig. 3. (а, d) – model vertical distributions of relative dielectric permittivity. (b, e) – received signal ( ) ( )E f s g s in quasi-logarithmic scale;
(c, f) – experimental A-scans (1) and (2) from Fig. 1.
4. reflects from the gradient ( ) ( )z z and comes back,
covering optical path
0
2 ( ) 2 ( ) ,
z
p s d s ct .
An analytical simplification has been reached in [2] by
applying asymptotic evaluation of the integral (1) under the
assumption of a relatively short probing pulse:
( )
1 2
3 2
0
( )
1
( ) [ 2 ( )] ( ) .
8
m
z s
z z s
g s h s p z p z dz
(2)
where ( ) ( )h s f s ds .
Although a number of relevant factors, such as antenna
radiation pattern, probing pulse divergence, material losses,
etc. are not taken into account, the approximate solution (1-
2) provides a good qualitative descriptions of deep GPR
echoes with elementary computational means. Consider two
model dielectric permittivity profiles described by the
Gaussian integral (“error function”):
0 1 1 0 0 1
1 0
2
( ) erf
2 2 6
z z z
z
z z
(3)
The probing pulse is chosen as ( ) ( )sin ( )f s s s , with
( ) 2 (1 )a s
s e
. The first set of parameters:
0 1 0 19, 6, 15, 35z z describes a realistic smooth
transition from a wet subsurface soil to a drier limestone
bedrock – see Fig. 3 (a). By comparing the simulated return
signal with the experimental A-scan (1) from Fig. 1 – cf. Fig
3 (b-c) we can judge that such a simple ad hoc model
surprisingly well describes the measured results. The second
example, with the parameter set
0 1 0 18, 16, 10, 20z z simulating a smooth
transition from subsurface soil to wet clay or silt mass filling
the former riverbed demonstrates even better agreement with
the experiment – see Fig. 3 (d-f).
These numerical examples support the intuitive
interpretation of deep GPR data by experienced practical
geophysicists and yield temptation to use approximate
formulas (1-2) for quantitative assessment of the subsurface
medium electrical properties. Formally, it is evidently
possible as the differential equation (2) admits analytical
inversion relative to the unknown vertical permittivity
distribution ( )z , provided the radar return signal ( )g s and
the initial pulse ( )f s are known [2]. Of course, a major
theory refinement is needed in order to convert it in a reliable
practical tool. A part of this work has been done in our recent
paper [7] taking into account the antenna radiation pattern
and wave divergence in the horizontally layered subsurface
medium.
A more difficult problem is taking into account the
transient current distribution in the transmitter antenna,
depending not only on its geometry and material but also on
the properties of the underlying ground, unknown a priory
and varying along the survey path. A promising idea, put
forward in [11], consists in the use of the first coming surface
wave registered by the receiver antenna for the assessment of
the probing pulse waveform radiated downwards
IV. CONCLUSION
In this work we tried to combine practical experience of
GPR applications in near-surface geophysics with a semi-
analytical simulation approach stemming from quantum
mechanics. It was shown that the simplest 1D time-domain
version of coupled-WKB approximation produces radar
return patterns similar to the experimental DPR echo signals.
So we can expect that more elaborated propagation and
backscattering models (including horizontal gradients, wave
divergence and absorption) based on coupled-WKB theory
may become a useful simulation and inversion tool of deep
GPR probing.
ACKNOWLEDGMENT
This work was supported in part by the Russian
Foundation for Basic Research in the framework of the
scientific project No. 18-02-00185.
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