THREE‐DIMENSIONAL RESISTIVITY AND INDUCED‐POLARIZATION MODELING USING BURIED ELECTRODES

Geophysics ◽  
1977 ◽  
Vol 42 (5) ◽  
pp. 1006-1019 ◽  
Author(s):  
Jeffrey J. Daniels
Keyword(s):  
Electrical Properties ◽  
Apparent Resistivity ◽  
Three Dimensional ◽  
Equipotential Surface ◽  
Induced Polarization ◽  
The Body ◽  
Surface Electrode ◽  
Surface Integral ◽  
Drill Holes ◽  
Resistivity Modeling

The three‐dimensional induced‐polarization and resistivity‐modeling problem for buried source and receiver electrodes is solved by using a modified form of Barnett’s surface‐integral technique originally developed for surface‐electrode configurations. Six different buried electrode configurations are considered in this study: three types of hole‐to‐hole configurations, hole‐to‐surface and surface‐to‐hole configurations, and the single hole (bipole‐bipole) configuration. Results show there is no “best” method for all situations encountered in the field. The choice of method depends upon depth of the body, spacing of drill holes, and electrical properties of the body. In hole‐to‐hole measurements, the geometric factor (necessary for the computation of the apparent resistivity) becomes infinitely large or infinitely small whenever the receiving bipole is placed at a depth so that it lies on a zero equipotential surface. This leads to the formation of apparent resistivity anomalies that are extremely sensitive to the presence of the body but that are also complicated and not easily correlated with the position of the body. It is shown that diagnostic and easily interpretable anomalies are obtained by selecting the proper source‐receiver configurations.

THREE‐DIMENSIONAL INDUCED POLARIZATION AND ELECTROMAGNETIC MODELING

Geophysics ◽  
1975 ◽  
Vol 40 (2) ◽  
pp. 309-324 ◽  
Author(s):  
Gerald W. Hohmann
Keyword(s):  
Integral Equation ◽  
Green's Functions ◽  
Green’S Functions ◽  
Three Dimensional ◽  
Induced Polarization ◽  
The Body ◽  
Scale Model ◽  
Two Dimensional ◽  
Electromagnetic Modeling ◽  
The Earth

The induced polarization (IP) and electromagnetic (EM) responses of a three‐dimensional body in the earth can be calculated using an integral equation solution. The problem is formulated by replacing the body by a volume of polarization or scattering current. The integral equation is reduced to a matrix equation, which is solved numerically for the electric field in the body. Then the electric and magnetic fields outside the inhomogeneity can be found by integrating the appropriate dyadic Green’s functions over the scattering current. Because half‐space Green’s functions are used, it is only necessary to solve for scattering currents in the body—not throughout the earth. Numerical results for a number of practical cases show, for example, that for moderate conductivity contrasts the dipole‐dipole IP response of a body five units in strike length approximates that of a two‐dimensional body. Moving an IP line off the center of a body produces an effect similar to that of increasing the depth. IP response varies significantly with conductivity contrast; the peak response occurs at higher contrasts for two‐dimensional bodies than for bodies of limited length. Very conductive bodies can produce negative IP response due to EM induction. An electrically polarizable body produces a small magnetic field, so that it is possible to measure IP with a sensitive magnetometer. Calculations show that horizontal loop EM response is enhanced when the background resistivity in the earth is reduced, thus confirming scale model results.

IP AND RESISTIVITY TYPE CURVES FOR THREE‐DIMENSIONAL BODIES

Geophysics ◽  
1969 ◽  
Vol 34 (4) ◽  
pp. 615-632 ◽  
Author(s):  
K. Dieter ◽  
N. R. Paterson ◽  
F. S. Grant
Keyword(s):  
Arbitrary Shape ◽  
Apparent Resistivity ◽  
Three Dimensional ◽  
Spherical Shape ◽  
The Body ◽  
Electrode Arrays ◽  
Method Of Least Squares ◽  
Straightforward Manner ◽  
Type Curves ◽  
Actual Field

A new method for calculating anomaly patterns and type curves of apparent resistivity and apparent chargeability over three‐dimensional bodies imbedded in a half‐space is practicable. The solution of the boundary‐value problem for a point source of current near a body of arbitrary shape in the form of an inhomogeneous integral equation is solved numerically by the method of least squares. The solution is then used to construct the apparent resistivity and apparent chargeability functions for three and four‐electrode arrays in the vicinity of the body in a straightforward manner. Type curves show the application to an actual field example. Finally, some simple, direct aids for interpreting anomalies over mineralized zones of compact (i.e. roughly spherical) shape result. This study represents the results of the first phase of a continuing program of research into resistivity and IP interpretation theory.

On sensitivity of surface‐to‐borehole resistivity measurements to the attitude and the depth to center of a three‐dimensional spheroid

Geophysics ◽  
1985 ◽  
Vol 50 (7) ◽  
pp. 1173-1178 ◽  
Author(s):  
F. W. Yang ◽  
S. H. Ward
Keyword(s):  
Apparent Resistivity ◽  
Current Source ◽  
Three Dimensional ◽  
The Body ◽  
Simple Method ◽  
Pilot Studies ◽  
Resistivity Measurements ◽  
Oblate Body ◽  
A Current

Borehole‐to‐surface and surface‐to‐borehole resistivity measurements are versatile but not totally tested methods for detecting anomalies in the vicinity of a borehole. The former method has been discussed by several authors (Alfano, 1962; Merkel, 1971; Merkel and Alexander, 1971; Barnett, 1972; Snyder and Merkel, 1973; Snyder, 1976; Daniels, 1977, 1978, and 1983), but the latter has not received much attention. Morrison (1971) and Daniels (1977) are among the few who have addressed the problem. Each method has its own advantages. Surface‐to‐borehole resistivity measurements are made by placing a current source on the surface and measuring the apparent resistivity in a borehole in which the measuring electrodes are closer to the body than in the borehole‐to‐surface case. Pilot studies presented here suggest that the surface‐to‐borehole method can provide indicators of the attitude and the depth to the center of a body. This paper illustrates a simple method for qualitatively determining the attitude and the depth to the center of a body for a thin three‐dimensional (3-D) conductive oblate body with the surface‐to‐borehole technique. Attitude conveys the orientation of the body— horizontal, vertical dipping toward a borehole, or dipping away from a borehole.

ANALYTIC MODELS FOR THE INTERPRETATION OF ELECTRICAL SURVEYS USING BURIED CURRENT ELECTRODES

Geophysics ◽  
1973 ◽  
Vol 38 (3) ◽  
pp. 513-529 ◽  
Author(s):  
Donald D. Snyder ◽  
Richard M. Merkel
Keyword(s):  
Apparent Resistivity ◽  
Three Dimensional ◽  
Drill Hole ◽  
Surface Electrode ◽  
Sphere Model ◽  
Current Electrode ◽  
Anomaly Pattern ◽  
Lateral Offset ◽  
Analytic Models ◽  
A Current

The IP response and the apparent resistivity resulting from a buried current pole in the presence of a stratigraphic target and a three‐dimensional target have been studied. The targets were modeled using a layered model to simulate the stratigraphic target and a buried sphere model to simulate the three‐dimensional target. The results show that there is a substantial increase in the response of the target measured at the surface for current electrode depths of greater than half the depth to the top of the target. A larger anomalous response is of particular importance when dealing with deeply buried targets from which little or no response is measured using conventional surface electrode methods. Furthermore, the results indicate that a survey around a drill hole containing a current electrode can be used to outline mineralization in the immediate vicinity of the drill hole. Some empirical observations resulting from our study are presented which relate the lateral offset of the target from the drill hole and its depth to characteristics of the anomaly pattern as measured on the surface.

scholarly journals Three‐dimensional mise‐à‐la‐masse modeling applied to mapping fracture zones

Geophysics ◽  
1986 ◽  
Vol 51 (1) ◽  
pp. 98-113 ◽  
Author(s):  
Craig W. Beasley ◽  
Stanley H. Ward
Keyword(s):  
Cross Section ◽  
Apparent Resistivity ◽  
Three Dimensional ◽  
The Body ◽  
Near Miss ◽  
Geothermal System ◽  
Volume Integral ◽  
Fracture Zones ◽  
Current Case ◽  
Similar Shape

A numerical scheme applying the method of volume integral equations has been developed for borehole‐to‐borehole and borehole‐to‐surface modeling of the apparent resistivity response of a thin conductive body in a half‐space; the inhomogeneity simulates a fracture zone in a geothermal system. The algorithm is applicable for the direct‐current case when the buried electrode is either inside (mise‐à‐la‐masse) or outside (near‐miss) the body. In implementing the scheme, the integral equation is transformed into a matrix equation as a result of discretizing the inhomogeneity into rectangular cells. All physical properties are assumed constant within each cell. The rectangular cells are used through‐out execution of the algorithm. The computed surface and subsurface apparent resistivity responses are examined for bodies of similar shape and size but with different orientations: (1) vertical, (2) horizontal, (3) dipping at 60 degrees, and (4) dipping at 30 degrees. The four bodies produce apparent resistivity cross‐section plots which differ little from each other except in orientation. Varying the depth to the top of a body does not significantly alter the subsurface apparent resistivity response in the vicinity of the body. In both section and plan views, estimates of orientation, areal extent, and dip can often be made. The maximum depth at which a body can be located and still produce a detectable surface anomaly is dependent upon the position of the buried electrode and upon the contrast in conductivity. Locating the buried electrode just outside the body does not significantly alter the results from those when the electrode is embedded in the inhomogeneity. However, the similarity between the results of these two cases decreases as the distance between the electrode and the body is increased.

Topographic effects in resistivity and induced‐polarization surveys

Geophysics ◽  
1980 ◽  
Vol 45 (1) ◽  
pp. 75-93 ◽  
Author(s):  
Richard C. Fox ◽  
Gerald W. Hohmann ◽  
Terry J. Killpack ◽  
Luiz Rijo
Keyword(s):  
Finite Element ◽  
Apparent Resistivity ◽  
Induced Polarization ◽  
The Body ◽  
Topographic Effects ◽  
Finite Element Program ◽  
Irregular Terrain ◽  
Element Program ◽  
Polarizable Body ◽  
Central High

We have made a systematic study of dipole‐dipole apparent resistivity anomalies due to topography and of the effect of irregular terrain on induced‐polarization (IP) anomalies, using a two‐dimensional (2-D), finite‐element computer program. A valley produces a central apparent resistivity low in the resistivity pseudosection, flanked by zones of higher apparent resistivity. A ridge produces just the opposite anomaly pattern—a central high flanked by lows. A slope generates an apparent resistivity low at its base and a high at its top. Topographic effects are important for slope angles of 10 degrees or more and for slope lengths of one dipole‐length or greater. The IP response of a homogeneous earth is not affected by topography. However, irregular terrain does affect the observed IP response of a polarizable body due to variations in the distance between the electrodes and the body. These terrain‐induced anomalies can lead to erroneous interpretations unless topography is included in numerical modeling. A field case demonstrates the importance of including topography, where it is significant, in interpretation models. A technique for correcting apparent resistivity for topographic effects uses the finite‐element program to compute correction factors.

Scanning electron microscopy of freeze-fractured prescapular lymph node of caprine

1984 ◽  
Vol 42 ◽  
pp. 244-245
Author(s):  
O. Faroon ◽  
F. Al-Bagdadi ◽  
T. G. Snider ◽  
C. Titkemeyer
Keyword(s):  
Lymph Node ◽  
Lymph Nodes ◽  
Lymphatic System ◽  
Three Dimensional ◽  
Meat Products ◽  
The Body ◽  
Morphological Data ◽  
The World ◽  
Cellular Constituent ◽  
Scanning Electron

The lymphatic system is very important in the immunological activities of the body. Clinicians confirm the diagnosis of infectious diseases by palpating the involved cutaneous lymph node for changes in size, heat, and consistency. Clinical pathologists diagnose systemic diseases through biopsies of superficial lymph nodes. In many parts of the world the goat is considered as an important source of milk and meat products.The lymphatic system has been studied extensively. These studies lack precise information on the natural morphology of the lymph nodes and their vascular and cellular constituent. This is due to using improper technique for such studies. A few studies used the SEM, conducted by cutting the lymph node with a blade. The morphological data collected by this method are artificial and do not reflect the normal three dimensional surface of the examined area of the lymph node. SEM has been used to study the lymph vessels and lymph nodes of different animals. No information on the cutaneous lymph nodes of the goat has ever been collected using the scanning electron microscope.

Clinical Utility of an Exoskeleton Robot Using 3-Dimensional Scanner Modeling in Burn Patient: A Case Report

2021 ◽  
Author(s):  
So Young Joo ◽  
Seung Yeol Lee ◽  
Yoon Soo Cho ◽  
Sangho Yi ◽  
Cheong Hoon Seo
Keyword(s):  
Burn Injury ◽  
Hand Function ◽  
Three Dimensional ◽  
The Body ◽  
3D Technology ◽  
Early Management ◽  
3 Dimensional ◽  
Exoskeleton Robot ◽  
Physical Abilities ◽  
Upper Limb Dysfunction

Abstract Hands are the part of the body that are most commonly involved in burns, and the main complications are finger joint contractures and nerve injuries. Hypertrophic scarring cannot be avoided despite early management of acute hand burn injuries, and some patients may need application of an exoskeleton robot to restore hand function. To do this, it is essential to individualize the customization of the robot for each patient. Three-dimensional (3D) technology, which is widely used in the field of implants, anatomical models, and tissue fabrication, makes this goal achievable. Therefore, this report is a study on the usefulness of an exoskeleton robot using 3D technology for patients who lost bilateral hand function due to burn injury. Our subject was a 45-year-old man with upper limb dysfunction of 560 days after a flame and chemical burn injury, with resultant impairment of manual physical abilities. After wearing an exoskeleton robot made using 3D printing technology, he could handle objects effectively and satisfactorily. This innovative approach provided considerable advantages in terms of customization of size and reduction in manufacturing time and costs, thereby showing great potential for use in patients with hand dysfunction after burn injury.

scholarly journals Virtual Archaeology of Death and Burial: A Procedure for Integrating 3D Visualization and Analysis in Archaeothanatology

2021 ◽  
Vol 7 (1) ◽  
pp. 540-555
Author(s):  
Hayley L. Mickleburgh ◽  
Liv Nilsson Stutz ◽  
Harry Fokkens
Keyword(s):  
Spatial Information ◽  
3D Visualization ◽  
Rapid Development ◽  
Three Dimensional ◽  
3D Models ◽  
The Body ◽  
Test Case ◽  
Archaeology Of Death ◽  
Human Burials ◽  
3D Information

Abstract The reconstruction of past mortuary rituals and practices increasingly incorporates analysis of the taphonomic history of the grave and buried body, using the framework provided by archaeothanatology. Archaeothanatological analysis relies on interpretation of the three-dimensional (3D) relationship of bones within the grave and traditionally depends on elaborate written descriptions and two-dimensional (2D) images of the remains during excavation to capture this spatial information. With the rapid development of inexpensive 3D tools, digital replicas (3D models) are now commonly available to preserve 3D information on human burials during excavation. A procedure developed using a test case to enhance archaeothanatological analysis and improve post-excavation analysis of human burials is described. Beyond preservation of static spatial information, 3D visualization techniques can be used in archaeothanatology to reconstruct the spatial displacement of bones over time, from deposition of the body to excavation of the skeletonized remains. The purpose of the procedure is to produce 3D simulations to visualize and test archaeothanatological hypotheses, thereby augmenting traditional archaeothanatological analysis. We illustrate our approach with the reconstruction of mortuary practices and burial taphonomy of a Bell Beaker burial from the site of Oostwoud-Tuithoorn, West-Frisia, the Netherlands. This case study was selected as the test case because of its relatively complete context information. The test case shows the potential for application of the procedure to older 2D field documentation, even when the amount and detail of documentation is less than ideal.

scholarly journals Petiole-Lamina Transition Zone: A Functionally Crucial but Often Overlooked Leaf Trait

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 774
Author(s):  
Max Langer ◽  
Thomas Speck ◽  
Olga Speck
Keyword(s):  
Transition Zone ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Body Plan ◽  
The Body ◽  
Vascular Bundles ◽  
Cross Sectional ◽  
Thin Sections ◽  
Transition Zones ◽  
The Cross

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.

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