Shaft-rate Electric Field Research Articles

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

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.

Mixed Electric Field of Multi-Shaft Ship Based on Oxygen Mass Transfer Process under Turbulent Conditions

The theoretical basis for a multi-physics coupling modeling involving a turbulence flow field and a ship’s electric field was analyzed using the principles of electrochemistry and hydrodynamics. Considering the mass transfer of oxygen in the cathode reaction of electrochemical corrosion, the boundary element method was adopted to construct a corrosion electric field model for a multi-shaft ship under navigation. After dissecting the equivalent circuit resistance of the mechanical structure of a ship’s shaft, the initial phase difference of the equivalent resistance between different shafting systems of a multi-shaft ship was analyzed to reveal the regularity of variation of the ship corrosion mixed electric field, when the contact positions of the shaft grounding device were different. A ship model experiment was conducted to verify the correctness of the simulation model. As shown in the results, when the initial phase difference of two-shaft ship shafting equivalent resistance increased from 0° to 45°, 90°, 135°, and 180°, the amplitude of the ship’s mixed electric field varied by less than 3.7%, which was practically negligible. However, the amplitude of the ship’s shaft-rate electric field decreased by 8.30%, 25.4%, 50.2%, and 88.0%, respectively. Moreover, the minimum value of the shaft-rate electric field accounted for 4.11% of the maximum value. This significantly increased the difficulty of marine target detection based on electric field sensors.

Application of adaptive line enhancer based on NLMS algorithm in shaft-rate electric field signal detection

There is lots of useful signal feature in ship’s shaft-rate electric field. Extracting the signal feature is vital in underwater target recognition. In order to extract the feature of the shaft-rate electric field, the shaft-rate electric field is processed by ALE based on NLMS. The improved NLMS algorithm is proposed to construct an adaptive line-spectrum enhancer, and then the measured data of shaft-rate electric field is processed by ALE. The results show that the algorithm can effectively separate the weak shaft frequency electric field signal from the broadband background noise at low SNR. Compared with the ordinary ALE, the algorithm has more significant effect in improving SNR, faster convergence speed and smaller steady-state error, which greatly improves the detection ability of ship shaft frequency electric field.

Detection of Ship Shaft-rate Electromagnetic Field Signal Based on NLMS Algorithm

Ship shaft-rate electromagnetic field signal contains a lot of valuable target feature information, and effectively extracting its line spectrum components plays an extremely important role in underwater target recognition. In order to effectively separate the characteristic line spectrum of ship shaft-rate electromagnetic field from broadband background noise, this paper studies and analyzes the shaft-rate electric field by using the line spectrum enhancement algorithm based on adaptive filtering. Firstly, the application principle of adaptive line spectrum enhancement and NLMS algorithm in ship shaft-rate signal detection is briefly described. Then, an adaptive line spectrum enhancer is constructed according to the improved NLMS algorithm, and the obtained shaft-rate electric field data are processed and analyzed by this method. Finally, it is verified by simulation data and experimental data. The results show that the algorithm can effectively suppress the background noise, significantly improve the signal-to-noise ratio, and enhance the detection ability of ship electromagnetic field signals in practical applications.

Real-Time Suppression Technology Research on Shaft-Rate Electric Field

To reduce the impact of shaft-rate electric field (SRE) on the concealment of the ship, the SRE related ship electrical equivalent model is established, and the electrical properties are studied based on the analysis of the mechanism of SRE of the ship in this paper. The ship SRE real-time suppression is proposed based on the compensated negative potential and the real-time close-loop system for the ship SRE suppression is designed. The extremely low frequency electric field strength is reduced greatly, and the shaft-rate and its harmonics field are eliminated ultimately. Experimental results show that the ship SRE can be suppressed effectively by the system, and the concealment of the ship is enhanced.

Research on the Ship Electrical Properties of Shaft-Rate Electric Field

In order to reduce the impact of shaft-rate electric field (SRE) on the concealment of the ship, the factors that influence shaft-rate electric field are studied based on the analysis of its energy source. The ship electrical equivalent model is established by analyzing the structure of ship shafts, and on this basis, the electrical properties of the ship shafting is analyzed, laying the theoretical foundation for the study of shaft-rate electric field. It is shown that the bearing contact impedance changing is the important part of the ship shaft structure electricity analysis among the factors and its analysis is the base of research on shaft-rate electric field restrains technology.

Real-Time Suppression Research of Shaft-Rate Electric Field Based on the Compensated Negative Potential

To reduce the impact of shaft-rate electric field (SRE) on the concealment of the ship, the ship SRE real-time suppression is proposed based on the compensated negative potential and the real-time close-loop system for the ship SRE suppression is designed and realized£¬which greatly promoted the development of ship SRE suppression technique.

Experimental Verification of the Suppression Effect of Ship Shaft-Rate Electric Field

To reduce the impact of shaft-rate electric field (SRE) on the concealment of the ship, The electric field immunity test is simulated with the laboratory scale model ship based on the analysis of the energy source of SRE. Experimental results show that the ship SRE can be suppressed effectively by the system, and the concealment of the ship is enhanced.