A Magnetic Field Separation Technique for a Scaled Model Ship through an Earth's Magnetic Field Simulator

Chung, Hyun-Ju; Yang, Chang-Seob; Jung, Woojin

doi:10.4283/jmag.2015.20.1.062

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…The authors in this paper do not present an approach that compares it with other existing ones in terms of advantages and disadvantages. The elements of the proposed approach in the paper are based on partial state-of-the-art techniques 18 , 22 – 27 . The authors in this paper use the solution developed in their previous works 28 to scale signatures determined on the measurement range (in the presence of strong permanent magnetization of ship) to any place on the Earth.…”

Section: Introductionmentioning

confidence: 99%

“…The multi-dipole model of the ship allows to separate its signatures related with permanent and induced magnetization 18 , 22 – 27 , 33 . This separation can be obtained using an optimization method which compares the ship signatures measured or calculated using the FEM method with those obtained from the multi-dipole model based on the magnetic data along the PKS lines in cardinal ship courses for two different values of the vertical external magnetic field 28 .…”

Section: Introductionmentioning

confidence: 99%

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Minimization of a ship's magnetic signature under external field conditions using a multi-dipole model

Woloszyn,

Tarnawski

2024

Sci Rep

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The paper addresses the innovative issue of minimizing the ship's magnetic signature under any external field conditions, i.e., for arbitrary values of ambient field modulus and magnetic inclination. Varying values of the external field, depending on the current geographical location, affect only the induced part of ship's magnetization. A practical problem in minimizing the ship signature is separating permanent magnetization from induced magnetization. When the ship position changes, a signature measurement has to be made under new magnetic field conditions to update the currents in the coils. This is impractical or even difficult to do (due to the need for a measuring ground), so there is a need to predict the ship's magnetization value in arbitrary geographical location conditions based on the reference signature determined on the measuring ground. In particular, the model predicting the signatures at a new geographical location must be able to separate the two types of magnetization, as permanent magnetization is independent of external conditions. In this paper, a FEM model of the vessel is first embedded in an external field and permanent magnetization is simulated using DC coils placed inside the model. Then, using the previously developed rules for data acquisition and determination of model parameters, a multi-dipole model is synthesized in which the induced and permanent parts are separated. The multi-dipole model thus developed has been successfully confronted with the initial model in FEM environment. The separation of permanent and induced magnetization allows the latter to be scaled according to new values of the external field. In the paper, the situation of determining a signature at one geographical position and its projection onto two other positions is analyzed. Having determined the signature with a high degree of accuracy anywhere in the world, it is possible to perform classical signature minimization by determining DC currents in coils placed inside the ship's hull. The paper also analyzes the effectiveness of ship's signature minimization and the influence of ship's course on the signature value. The advantage of the method presented in this paper is an integrated approach to the issue of scaling and minimization of ship magnetic signature, which has not been presented in the literature on such a scale before.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Minimization of a ship's magnetic signature under external field conditions using a multi-dipole model

Woloszyn,

Tarnawski

2024

Sci Rep

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“…This is done in Experiment 1 for a square steel plate without defect. For an object of any other geometry, the permanent magnetic field can be filtered out by repeating the measurements in zero magnetic field by using a magnetic field simulator, which has been done in the past by researchers focusing on reducing the magnetic signature of naval ships [19,20]. This is done in Experiment 2 for a square steel plate with a slit.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Structural Steels for Simulation of Crack Monitoring by Finite Element Method

Horst

Kaminski

2019

J Nondestruct Eval

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The metal magnetic memory method is a novel technique for monitoring fatigue cracks in steel structures, which can reduce operational expenses and increase safety by minimizing inspections. The crack geometry can be identified by measuring the self magnetic flux leakage, which is induced by the Earth's magnetic field and the permanent magnetization. The finite element method can be used to simulate the induced magnetic field around cracks to help interpret the self magnetic flux leakage measurements, but it is unclear what material properties to use. This study aims to determine the magnetic permeability of structural steel for accurate simulation of the induced magnetic field around cracks by the finite element method. The induced magnetic field was extracted from measurements above two square steel plates, one without defect and one with a straight slit, and compared with finite element results in function of the relative permeability. For both plates, a uniform relative permeability could be found for which experimental and numerical results were in good agreement. For the plate without defect and a relative permeability of 350, errors were within 20% and were concentrated around the plate's edges. For the plate with the slit and a relative permeability of 225, errors were within 5%.

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Developing high gradient magnetic separators for greener production: Principles, design, and optimization

Lin,

Li,

Lei

et al. 2023

Journal of Magnetism and Magnetic Materials

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A Magnetic Field Separation Technique for a Scaled Model Ship through an Earth's Magnetic Field Simulator

Cited by 6 publications

References 9 publications

Minimization of a ship's magnetic signature under external field conditions using a multi-dipole model

Minimization of a ship's magnetic signature under external field conditions using a multi-dipole model

Magnetic Properties of Structural Steels for Simulation of Crack Monitoring by Finite Element Method

Developing high gradient magnetic separators for greener production: Principles, design, and optimization

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