MAGNETIC SURVEYING USING HORIZONTAL GRADIENT VECTORS

Geophysics ◽  
1977 ◽  
Vol 42 (6) ◽  
pp. 1262-1264 ◽  
Author(s):  
S. Thyssen‐Bornemisza
Keyword(s):  
Magnetic Field ◽  
Unit Vector ◽  
Magnetic Potential ◽  
Horizontal Gradient ◽  
Magnetic Intensity ◽  
Total Field ◽  
Nonlinear Characteristics ◽  
Normal Magnetic Field ◽  
Vertical Gradients ◽  
Airborne Magnetic

It was pointed out some time ago (Bhattacharyya, 1965) that the total intensity anomaly of a magnetic field ΔT in the direction of the normal magnetic field of earth is expressed by the equation, [Formula: see text]Here ΔV denotes the anomaly of the magnetic potential and t the unit vector in the direction of earth’s undisturbed total field. Horizontal and vertical gradients observed along the tracks of airborne magnetic surveys were discussed by several authors (Wickerham, 1954; Glicken, 1955; Hood, 1965; Langan, 1966). These gradients are obtained from the formulas [Formula: see text] [Formula: see text]where the magnetic intensity differences are observed over horizontal and vertical intervals Δx and Δz between two sensors. However, this approach is only valid when the depth h of the causative body or structure is relatively large compared to Δx and Δz; thus in cases of shallow anomalies, the nonlinear characteristics of the anomalous magnetic field would distort the observed gradients and render interpretation of data very difficult.

THE GEOMAGNETIC GRADIOMETER

Geophysics ◽  
1967 ◽  
Vol 32 (5) ◽  
pp. 877-892 ◽  
Author(s):  
Howard A. Slack ◽  
Vance M. Lynch ◽  
Lee Langan
Keyword(s):  
Magnetic Field ◽  
Vertical Gradient ◽  
Diurnal Variations ◽  
Resolving Power ◽  
Magnetic Intensity ◽  
Geophysical Prospecting ◽  
Total Field ◽  
Optically Pumped ◽  
Magnetic Gradient ◽  
The Difference

The geomagnetic gradiometer is a new geophysical prospecting tool which measures directly the vertical gradient of the earth’s magnetic field and the total field intensity. The system is composed of two simultaneously recording, optically pumped and monitored magnetometer sensors suspended from a helicopter. The sensors are separated vertically by a known distance so that the magnetic gradient can be determined from the difference in total magnetic intensity between the two sensors. Since the gradient is measured directly, the gradiometer allows geophysicists to make better use of LaPlace’s and Euler’s equations. The gradiometer increases the value of magnetic prospecting by: (1) greatly increasing resolving power, (2) discriminating between intrabasement and suprabasement anomalies, and (3) eliminating problems caused by diurnal variations.

scholarly journals INCREASING THE EFFICIENCY OF MULTY-VARIANT CALCULATIONS OF ELECTROMAGNETIC FIELD DISTRIBUTION IN MATRIX OF A POLYGRADIENT SEPARATOR

2021 ◽  
Author(s):  
Jasim Mohmed Jasim Jasim ◽  
Iryna Shvedchykova ◽  
Igor Panasiuk ◽  
Julia Romanchenko ◽  
Inna Melkonova
Keyword(s):  
Magnetic Field ◽  
Field Distribution ◽  
Three Dimensional ◽  
Magnetic Potential ◽  
Geometric Parameters ◽  
Two Dimensional ◽  
Air Gaps ◽  
Vector Magnetic Potential ◽  
Electromagnetic Separator ◽  
The Magnetic Field

An approach is proposed to carry out multivariate calculations of the magnetic field distribution in the working gaps of a plate polygradient matrix of an electromagnetic separator, based on a combination of the advantages of two- and three-dimensional computer modeling. Two-dimensional geometric models of computational domains are developed, which differ in the geometric dimensions of the plate matrix elements and working air gaps. To determine the vector magnetic potential at the boundaries of two-dimensional computational domains, a computational 3D experiment is carried out. For this, three variants of the electromagnetic separator are selected, which differ in the size of the working air gaps of the polygradient matrices. For them, three-dimensional computer models are built, the spatial distribution of the magnetic field in the working intervals of the electromagnetic separator matrix and the obtained numerical values of the vector magnetic potential at the boundaries of the computational domains are investigated. The determination of the values of the vector magnetic potential for all other models is carried out by interpolation. The obtained values of the vector magnetic potential are used to set the boundary conditions in a computational 2D experiment. An approach to the choice of a rational version of a lamellar matrix is substantiated, which provides a solution to the problem according to the criterion of the effective area of the working area. Using the method of simple enumeration, a variant of the structure of a polygradient matrix with rational geometric parameters is selected. The productivity of the electromagnetic separator with rational geometric parameters of the matrix increased by 3–5 % with the same efficiency of extraction of ferromagnetic inclusions in comparison with the basic version of the device

Computational investigation of non-uniform magnetic field on thermal characteristic of nanofluid stream inside 180∘ elbow pipe

2021 ◽  
pp. 2150157
Author(s):  
Yu-Ming Chu ◽  
Rasoul Moradi ◽  
Amir Musa Abazari
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Average Nusselt Number ◽  
Uniform Magnetic Field ◽  
Thermal Characteristic ◽  
Flow Characteristics ◽  
Heat Rate ◽  
Magnetic Intensity ◽  
Computational Investigation ◽  
Major Focus

The thermal efficiency of the heat exchanger is substantial in chemical and mechanical systems. The presence of the non-homogeny magnetic field considerably enhances the heat rate of nanofluid stream. In this exploration, the presence of the non-uniform magnetic intensity on the heat rate of nanofluid stream is noted inside the 180[Formula: see text] elbow pipe. FVM is used to model the flow characteristics and temperature distribution through the 180[Formula: see text] elbow pipe. Our major focus is to demonstrate the main influences of the non-uniform FHD on flow stream and heat transfer of nanofluid in various inlet velocities and magnetic intensities. Achieved outcomes display that growing the magnetic intensity from 1e + 6 to 4e + 6 enhances the average Nusselt number about 30%. Our findings show that increasing the inlet velocity to Re = 100 decreases the magnetic effects about 17% on the heat transfer growth.

scholarly journals Magnetic Domain Transition of Adjacent Narrow Thin Film Strips with Inclined Uniaxial Magnetic Anisotropy

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 279
Author(s):  
Tomoo Nakai
Keyword(s):  
Magnetic Field ◽  
Easy Axis ◽  
Magnetic Domain ◽  
Magnetic Interaction ◽  
Individual Element ◽  
Typical Characteristic ◽  
Many Body ◽  
Uniaxial Magnetic Anisotropy ◽  
Line Arrangement ◽  
Normal Magnetic Field

This study deals a phenomenon of magnetic domain transition for the stepped magneto-impedance element. Our previous research shows that an element with 70° inclined easy axis has a typical characteristic of the domain transition, and the transition can be controlled by the normal magnetic field. In this paper, we apply this phenomenon and controlling method to the line arrangement adjacent to many body elements, in which mutual magnetic interaction exists. The result shows that the hidden inclined Landau–Lifshitz domain appears by applying a distributed normal field the same as an individual element.

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