On: “Nomogram for the direct interpretation of magnetic anomalies due to long horizontal cylinders,” by T. K. S. Prakasa Rao, M. Subrahmanyam, and A. Srikrishna Murty, (GEOPHYSICS, 51, 2156–2159, November 1986.)

Geophysics ◽  
1987 ◽  
Vol 52 (10) ◽  
pp. 1442-1443
Author(s):  
Ronald Green
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Horizontal Cylinder ◽  
Direct Interpretation ◽  
Horizontal Cylinders

In the article by T. K. S. Prakasa Rao, M. Subrahmanyam, and A. Srikrishna Murty, the trivial problem of interpreting the magnetic anomaly over a horizontal cylinder was examined and a set of nomograms to assist with the interpretation was presented. Prakasa Rao et al. begin their discussion with equation (1) from Gay (1965).

Nomogram for the direct interpretation of magnetic anomalies due to long horizontal cylinders

Geophysics ◽  
1986 ◽  
Vol 51 (11) ◽  
pp. 2156-2159 ◽  
Author(s):  
T. K. S. Prakasa Rao ◽  
M. Subrahmanyam ◽  
A. Srikrishna Murthy
Keyword(s):  
Direct Method ◽  
Linear Equations ◽  
Arbitrary Point ◽  
Magnetic Anomalies ◽  
Horizontal Cylinder ◽  
Empirical Method ◽  
Master Curves ◽  
Hilbert Transforms ◽  
Direct Interpretation ◽  
Horizontal Cylinders

One of the widely used geometrical configurations for magnetic interpretation is the long horizontal circular cylinder. Gay (1965) provides a set of master curves for the interpretation of magnetic anomalies of these bodies. Rao et al. (1973) formulates functions of the anomaly at several distances from an arbitrary point, and the linear equations thus formed are solved for coefficients related to the parameters of the causative body. Prakasa Rao and Murthy (1976) propose an empirical method for rapid interpretation. Atchuta Rao and Ram Babu (1980), Mohan et al. (1982), and Sampath Kumar and Prakasa Rao (1984) describe methods based on Hilbert transforms. Radhakrishna Murthy et al. (1980) propose a method based on two components of the anomalous magnetic field. With the exception of the direct method of Prakasa Rao and Murthy (1976), the other methods mentioned involve reduction of field curves and then matching with master curves, solving linear equations, performing Hilbert transformations, and computation of derivatives, respectively. Hence they are not suitable for direct and rapid interpretation. This note contains a simple nomogram for the magnetic effect due to an arbitrarily magnetized horizontal cylinder.

Relationship of magnetic anomalies due to subsurface features and the interpretation of sloping contacts

Geophysics ◽  
1980 ◽  
Vol 45 (1) ◽  
pp. 32-36 ◽  
Author(s):  
D. Atchuta Rao ◽  
H. V. Ram Babu ◽  
P. V. Sanker Narayan
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Horizontal Cylinder ◽  
Horizontal Derivative ◽  
Horizontal Cylinders ◽  
Relationship Of

A study of the magnetic anomalies produced by sloping geologic contacts, thin dikes, and horizontal cylinders has revealed that a single relationship exists among the magnetic anomalies created by them. The magnetic anomaly due to a horizontal cylinder, the first horizontal derivative of the magnetic anomaly due to a thin dike, and the second horizontal derivative of the magnetic anomaly due to a sloping contact are found to be identical in shape. Gay (1963, 1965) presented standard curves to interpret the magnetic anomalies over long tabular bodies (1963) and long horizontal cylinders (1965). It is shown here that the same curves can also be used to interpret the total, vertical and horizontal magnetic anomalies due to sloping geologic contacts.

Magnetic interpretation using a least-squares, depth-shape curves method

Geophysics ◽  
2005 ◽  
Vol 70 (3) ◽  
pp. L23-L30 ◽  
Author(s):  
El-Sayed M. Abdelrahman ◽  
Khalid S. Essa
Keyword(s):  
Least Squares ◽  
Magnetic Anomaly ◽  
Least Squares Method ◽  
Random Noise ◽  
Synthetic Data ◽  
Theoretical Data ◽  
Magnetic Anomalies ◽  
Shape Factors ◽  
Characteristic Points ◽  
Horizontal Cylinders

We have developed a least-squares approach to depth determination from residual magnetic anomalies caused by simple geologic structures. By normalizing the residual magnetic anomaly using three characteristic points and their corresponding distances on the anomaly profile, the problem of determining depth from residual magnetic anomalies has been transformed into finding a solution to a nonlinear equation of the form z = f(z). Formulas have been derived for spheres, horizontal cylinders, thin dikes, and contacts. The method is applied to synthetic data with and without random noise. We have also developed a method using depth-shape curves to simultaneously define the shape and depth of a buried structure from a residual magnetic anomaly profile. The method is based on determining the depth from the normalized residual anomaly for each shape factor using the least-squares method mentioned above. The computed depths are plotted against the shape factors on a graph. The solution for the shape and depth of the buried structure is read at the common intersection of the depth-shape curves. The depth-shape curves method was successfully tested on theoretical data with and without random noise and applied to a known field example from Ontario.

A General Correlation for Pool Film Boiling Heat Transfer From a Horizontal Cylinder to Subcooled Liquid: Part 2—Experimental Data for Various Liquids and Its Correlation

1990 ◽  
Vol 112 (2) ◽  
pp. 441-450 ◽  
Author(s):  
A. Sakurai ◽  
M. Shiotsu ◽  
K. Hata
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Analytical Solution ◽  
Boiling Heat Transfer ◽  
Radiation Effects ◽  
Approximate Analytical Solution ◽  
Horizontal Cylinder ◽  
Film Boiling ◽  
System Pressure ◽  
Horizontal Cylinders

Experimental data of pool film boiling heat transfer from horizontal cylinders in various liquids such as water, ethanol, isopropanol, Freon-113, Freon-11, liquid nitrogen, and liquid argon for wide ranges of system pressure, liquid subcooling, surface superheat and cylinder diameter are reported. These experimental data are compared with a rigorous numerical solution and an approximate analytical solution derived from a theoretical model based on laminar boundary layer theory for pool film boiling heat transfer from horizontal cylinders including the effects of liquid subcooling and radiation from the cylinder. A new correlation was developed by slightly modifying the approximate analytical solution to agree better with the experimental data. The values calculated from the correlation agree with the authors’ data within ± 10 percent, and also with other researchers’ data for various liquids including those with large radiation effects, though these other data were obtained mainly under saturated conditions at atmospheric pressure.

Analysis of Magnetic Anomaly Characteristics of Underground Non-Coplanar Cross-buried Iron Pipelines

2020 ◽  
Vol 25 (2) ◽  
pp. 223-233
Author(s):  
Pan Wu ◽  
Minghui Wei
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
Magnetic Dipole ◽  
Geomagnetic Field ◽  
Magnetic Anomalies ◽  
Buried Pipelines ◽  
Magnetic Declination ◽  
Magnetic Inclination ◽  
Basic Characteristics ◽  
Geomagnetic Intensity

The non-coplanar cross-buried pipelines are a common way of pipeline wiring. In order to investigate the magnetic anomaly characteristics of the non-coplanar cross-buried pipelines and guide the site operation, the influences of a series of factors on the magnetic anomaly of the non-coplanar cross-buried pipelines are analyzed. Based on the principle of magnetic dipole construction, a forward model is established for the magnetic anomaly characteristics of the subsurface non-coplanar cross-buried pipelines. The basic characteristics of magnetic anomaly for the non-coplanar cross-buried pipelines are defined. The influences of geomagnetic parameters (geomagnetic intensity, geomagnetic inclination, and geomagnetic declination), pipeline parameters (thickness, magnetic susceptibility), and cross angle of pipelines on the characteristics of magnetic anomalies are analyzed. The results show that the shape of the total magnetic anomaly is mainly affected by the magnetic inclination, and the curve of magnetic anomaly at ± I site shows some symmetry. The amplitude is approximately linearly affected by the total geomagnetic field, magnetic declination, pipeline thickness, material magnetic susceptibility, and pipeline cross angle. There is a periodic change of the amplitude with the increase of geomagnetic inclination (−90°–>90°). The crest-trough distance is mainly affected by geomagnetic inclination, magnetic declination, thickness, magnetic susceptibility, and pipeline cross angle. A more accurate measurement can be achieved if the direction of the pipelines is roughly measured and then the number of measurement points is augmented near the intersection of pipelines and the measurement lines. Present work obtains the equivalent magnetic dipole units by segmenting pipelines. The magnetic anomaly characteristics of non-coplanar crossed iron pipelines are successfully simulated. The numerical results are in accordance with the experimental analysis.

scholarly journals TWO-PHASE FLOW SIMULATIONS OF SCOUR AROUND VERTICAL AND HORIZONTAL CYLINDERS

2018 ◽  
pp. 22
Author(s):  
Tim Nagel ◽  
Julien Chauchat ◽  
Cyrille Bonamy ◽  
Antoine Mathieu ◽  
Xiaofeng Liu ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Two Phase Flow ◽  
Numerical Data ◽  
Horizontal Cylinder ◽  
Transport Processes ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Solver ◽  
Sediment Bed ◽  
Horizontal Cylinders

Scour around structures is a major engineering issue that requires a detailed description of the flow field as well as sediment transport processes. Due to enhanced suspended load associated with vortices generated around structures, sediment transport cannot be solely related to bed shear stress, such as Shields parameter based formula. In order to address this issue, we used a multi-dimensional two-phase flow solver, sedFoam-2.0 (Chauchat et al., GMD 2017) implemented under the open-source CFD toolbox OpenFOAM. Three configurations are studied and compared with experimental and numerical data from the literature. First, the 2D configurations of an horizontal cylinder lying on a sediment bed (Mao, 1986; Sumer et al., 2001) are investigated. Then, the 3D configuration of the scour around a vertical cylindrical pile reported by Roulund et al. (2005) for rigid-bed and live bed cases is investigated.

THE SEPARATION OF REMANENT FROM INDUCED MAGNETISM IN SITU

Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 779-796 ◽  
Author(s):  
N. E. Goldstein ◽  
S. H. Ward
Keyword(s):  
Magnetic Anomaly ◽  
Field Experiments ◽  
Magnetic Anomalies ◽  
Static Field ◽  
Observational Evidence ◽  
Field Direction ◽  
Dynamic Field ◽  
In Situ Separation

Remanent and induced magnetism both contribute to static field magnetic anomalies whereas only induced magnetism contributes to dynamic field magnetic anomalies. The theory whereby this phenomenon may be used to advantage for in‐situ separation of remanent from induced magnetism is presented as a prelude to observational evidence confirming the phenomenon. Four field experiments on Western States magnetic anomalies prove that it is possible to predict whether or not a given static field magnetic anomaly is primarily due to remanent or to induced magnetism. The limitations of the method include variability of micropulsation field direction, ellipticity, and intensity.

A computer program for interpreting vertical magnetic anomalies of spheres and horizontal cylinders

1973 ◽  
Vol 110 (1) ◽  
pp. 2056-2065 ◽  
Author(s):  
B. S. R. Rao ◽  
I. V. Radhakrishna Murthy ◽  
C. Visweswara Rao
Keyword(s):  
Computer Program ◽  
Magnetic Anomalies ◽  
Horizontal Cylinders

Magnetic anomaly of a circular lamina

Geophysics ◽  
1979 ◽  
Vol 44 (1) ◽  
pp. 102-107 ◽  
Author(s):  
S. K. Singh ◽  
R. Castro E. ◽  
M. Guzman S.
Keyword(s):  
Circular Cylinder ◽  
Closed Form ◽  
Gravity Anomaly ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Hankel Transform ◽  
Poisson’S Equation ◽  
Poisson's Equation ◽  
Gravity And Magnetic

Closed form expressions for the gravity anomaly of a circular lamina and the gravity and magnetic anomalies due to a vertical right circular cylinder have been obtained previously (Singh, 1977a; Singh, 1977b; Singh and Sabina, 1978) by a method which avoids complicated integrations commonly used in deriving such solutions (e.g., Nabighian, 1962; Rao and Radhakrishnamurty, 1966). The method involves use of the Fourier‐Hankel transform of Poisson’s equation. The final expressions are obtained in closed form by employing certain tabulated integrals.

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