Methods of Measuring the Low-Frequency Electric and Magnetic Fields of Ships

Zolotarevskii, Yu. M.; Bulygin, F. V.; Ponomarev, A. N.; Narchev, V. A.; Berezina, L. V.

doi:10.1007/s11018-006-0035-6

Cited by 11 publications

(5 citation statements)

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“…The use of different metal materials in various ship components, each with unique chemical properties, leads to variations in their respective electrode potential values. Upon contact with seawater, these components undergo electrochemical processes, leading to the creation of a corrosion current within the seawater's closed circuit [23]. To protect the hull from corrosion in seawater, besides using anti-corrosion coatings, a cathodic protection system utilizing sacrificial anodes and an external current is commonly utilized to create a protective current for corrosion prevention.…”

Section: Mechanism Of the Shaft-rate Electric Fieldmentioning

confidence: 99%

Ship Shaft-Rate Electric Field Signal Denoising Method Based on VMD-MSS

Wang,

Chi

et al. 2024

JMSE

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The presence of complex electromagnetic noise in the ocean significantly impacts the accuracy of ship shaft-rate electric field signal detection, necessitating the development of an effective denoising method to enhance detection precision. Nevertheless, traditional denoising methods encounter issues like low frequency resolution, challenging threshold configuration, and mode mixing. This study introduces a method that integrates variational mode decomposition (VMD) with multi-window spectral subtraction (MSS). The intrinsic mode functions (IMFs) of noisy signals are extracted using VMD, and the noise components within different IMFs are identified. The spectral features of both signal and noise within different IMFs are leveraged to eliminate noise signals via MSS. Subsequently, the denoised components of IMFs are rearranged to derive the denoised ship shaft-rate electric field signals, achieving noise reduction across various frequency bands. Following validation using simulation signals and empirical data, the noise reduction efficacy of VMD-MSS surpasses that of alternative methods, demonstrating robust performance even at low signal-to-noise ratios. The marine electromagnetic noise is effectively suppressed in the empirical data, while preserving the characteristics of ship’s shaft-rate signals, thereby validating the method’s efficacy and demonstrating its practical engineering value.

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Section: Mechanism Of the Shaft-rate Electric Fieldmentioning

confidence: 99%

Ship Shaft-Rate Electric Field Signal Denoising Method Based on VMD-MSS

Wang,

Chi

et al. 2024

JMSE

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“…Birsan argued that a low frequency electric field was basically generated by the cyclic rotation of the helices [ 20 ]. Zolotarevskii built a low frequency electric field measurement platform [ 21 ]. In underwater environments, the electric field signal is more stable than the acoustic signal.…”

Section: Introductionmentioning

confidence: 99%

Electric Field Detection System Based on Denoising Algorithm and High-Speed Motion Platform

Liu

Sun

Jiang

et al. 2022

Sensors

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Effective denoising can ensure fast and accurate target detection. This paper presents an electric field measurement system based on a high-speed motion platform, which was built to analyze the characteristics of low frequency electric field noise. An offshore test has shown that it is possible to detect a low-frequency electric field using a high-speed motion platform. Low frequency electric field noise was then collected to analyze its characteristics in terms of time and frequency domains. Based on the noise characteristics, complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) was improved and combined with an adaptive threshold algorithm for denoising and reconstructing target containing noise signals. As revealed in the results, the proposed algorithm achieved highly effective denoising to overcome the line spectrum detection failure resulting from a high-speed motion platform. The detection range had also been improved from the original 853 m to 1306 m, a 53.1% increase.

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“…In recent years, the corrosion related shaft-rate electromagnetic field source of the underwater moving targets has generated great interest. It produces extremely low frequency (ELF) emissions, which arise from the modulation of the corrosion currents of the targets and are expected to be of substantial value in poorly maintained platforms [ 4 , 5 , 6 , 7 , 8 , 9 ]. These emissions offer unique advantages over MAD signals as follows: first, at ELF detection frequencies, the usual electromagnetic noise interference should be much less of an issue than in the MAD frequency band; second, ELF emissions have relative low propagation attenuation which can be detected at long distances or deep locations in seawater.…”

Section: Introductionmentioning

confidence: 99%

A Novel Detection Method for Underwater Moving Targets by Measuring Their ELF Emissions with Inductive Sensors

Wang

Chen

et al. 2017

Sensors

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In this article, we propose a novel detection method for underwater moving targets by detecting their extremely low frequency (ELF) emissions with inductive sensors. The ELF field source of the targets is modeled by a horizontal electric dipole at distances more than several times of the targets’ length. The formulas for the fields produced in air are derived with a three-layer model (air, seawater and seafloor) and are evaluated with a complementary numerical integration technique. A proof of concept measurement is presented. The ELF emissions from a surface ship were detected by inductive electronic and magnetic sensors as the ship was leaving a harbor. ELF signals are of substantial strength and have typical characteristic of harmonic line spectrum, and the fundamental frequency has a direct relationship with the ship’s speed. Due to the high sensitivity and low noise level of our sensors, it is capable of resolving weak ELF signals at long distance. In our experiment, a detection distance of 1300 m from the surface ship above the sea surface was realized, which shows that this method would be an appealing complement to the usual acoustic detection and magnetic anomaly detection capability.

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Methods of Measuring the Low-Frequency Electric and Magnetic Fields of Ships

Cited by 11 publications

References 0 publications

Ship Shaft-Rate Electric Field Signal Denoising Method Based on VMD-MSS

Ship Shaft-Rate Electric Field Signal Denoising Method Based on VMD-MSS

Electric Field Detection System Based on Denoising Algorithm and High-Speed Motion Platform

A Novel Detection Method for Underwater Moving Targets by Measuring Their ELF Emissions with Inductive Sensors

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