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Identification Methods of Underwater Noise Sources Generated by Small Ships

100%
Gloza I.
Acta Physica Polonica A
|
2011
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vol. 119
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issue 6A
961-965
EN
In this work we were interested in the use for the localization of the ship noise sources in the water environment. Particular interest was dedicated to identifying of narrow band contribution to the total spectra of the ship hydroacoustic noise. The analyses were performed in time and frequency domain. The diesel engine, the electric motor and the propeller have notably been studied and the different frequencies connected to these devices have been listed. Extensive measurements were made of the underwater radiated noise of K1 and K2, small vessels powered by an electric and diesel engines. The discrete Fourier transform and the short time Fourier transform and sound intensity method were used for a precise analysis. The coherence function was also performed to associate each component of underwater noise with the vibrating part of the engine, which generates it. The measurement results obtained here have been later analyzed and a criticism of each method has been done, focusing on its advantages in the field of the identification of the noise sources.
2
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Experimental Investigation of Underwater Noise Produced by Ships by Means of Sound Intensity Method

100%
Gloza I.
|
EN
Ship noise is a one of most important part of the field of the acoustic environment. Its reduction and monitoring is a very important aspect in the performance of underwater acoustic systems and in the habitability of the vessel for the crew and passengers. In naval operations the noise radiated by a ship is also dominant source of information for underwater sonar weapons systems. Sound intensity is the vector quantity which informs us about the sound power flux, the direction of the sound source. The probe tracks the position of source and at the same time, measures the component of sound-intensity vector. Generally only one component of vector sound intensity was measured, perpendicular to a given measurement surface. The sound intensity of a moving source includes effects such as flow noise that are not present when the source is stationary. The accuracy of measuring acoustic intensity using two closely spaced hydrophones by correcting the phase mismatch error by measuring the transfer function between the two detector systems at the same time was examined. The two measuring hydrophone instrumentation systems were earlier carefully calibrated. Our results have been obtained using digital methods, where was used PULSE B&K measuring system.
3
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An Application of Fractional Brownian Motion to Vessel Identification Based on its Sound Spectrum

51%
Wiciak M., Gloza I., Jóźwiak R., Wiciak P.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1A
A-46-A-49
EN
The paper deals with the problem of vessel identification. The presented method is based on fractional Brownian analysis of vessel power spectrum. The measurements for three vessels were carried out with the use of a mobile measuring module in the Gulf of Gdansk; next, the information obtained from sound spectra was identified. Two classifiers connected with fractional Brownian motion were used: the first-order increments and the standard deviation. Finally, classification decision was made using the Mahalanobis distance. Numerical experiments were performed using MATLAB.
4
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Tracking Underwater Noise Sources with the Use of a Passive Method

51%
Gloza I., Buszman K., Józwiak R.
Acta Physica Polonica A
|
2013
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vol. 123
|
issue 6
1090-1093
EN
It is possible to track a source of noise by determining the intensity of sound that informs about the sound energy flow direction. One of the methods of determining the sound intensity of acoustic signals is the so-called gradient method in which the pressure is measured with the use of two hydrophones placed close to each other. Tetrahedral antenna consists of four hydrophones spaced at regular tetrahedron vertices so that distances between hydrophones are the same. The tetrahedral antenna determines six virtual points in the middle of each edge and allows using sound intensity calculation algorithm to determine the noise source bearing. In our experiment, the antenna was located 23 meters below the sea surface and a source of noise was moving over it. The object that was moving along a straight line with a specific course was equipped with a GPS receiver. This allowed comparison of the obtained targeting results with the real track of moving object. The paper presents the object tracking algorithm which was implemented in the MATLAB environment as well as some of the results of research carried out on passive source noise tracking.
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