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Wyszukujesz frazę "acoustic" wg kryterium: Temat


Tytuł:
An acoustic sea glider for deep-sea noise profiling using an acoustic vector sensor
Autorzy:
Sun, Qindong
Zhou, Hongkun
Powiązania:
https://bibliotekanauki.pl/articles/32889290.pdf
Data publikacji:
2022
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
acoustic sea glider
acoustic vector sensor
ambient sea noise
target detection
Opis:
An acoustic sea glider has been developed for ambient sea noise measurement and target detection through the deployment of an acoustic vector sensor (AVS). The glider was designed with three cabins connected in sequence and it can dive to depths exceeding 1200m. The AVS fixed on the glider measure acoustic pressure and particle velocities related to undersea noise, and the inner attitude sensors can effectively eliminate the estimation deviation of the direction of arrival. The inherent self-noises of the acoustic sea glider and AVS are presented respectively in respect to the Knudsen spectra of sea noise. Sea trial results indicate that the AVS could work well for undersea noise measurement when the glider is smooth sliding, and the target azimuth estimated by AVS after correction is remarkably consistent with the values measured by the GPS, and direction-finding errors are less than 10 degrees. The research in this paper shows that the acoustic sea glider is able to undertake tasks such as a wide range of underwater acoustic measurement and detection.
Źródło:
Polish Maritime Research; 2022, 1; 57-62
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic imaging of selected areas of Gdansk Bay with the aid of parametric echosounder and side-scan sonar
Autorzy:
Grelowska, G.
Kozaczka, E.
Szymczak, W.
Powiązania:
https://bibliotekanauki.pl/articles/963410.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
echolocation
acoustic imaging
seabed structure examination
Opis:
The article presents and analyses the data recorded during sounding of the Gdansk Bay seabed with the aid of a parametric echosounder and a side-scan sonar. The accuracy of seabed structure examination, as a condition for obtaining valuable results, requires correct configuration of echolocation devices and proper calibration of peripheral devices, such as the survey unit geographical position sensor – GPS, the navigation unit, the MRU-Z sensor of pitch, roll and heave, and the sound velocity meter, which deliver the data to the bathymetric measurement system. Parametric seabed profilers deliver two types of data: the envelope, and the detailed echo signal without processing. The envelope is used for data visualisation in the form of online echograms, while the echo signal is stored for further analyses, to be performed using dedicated software or, after relevant conversion, in arbitrary programming environment1. The presented data analysis is illustrated by selected sample images recorded by the parametric echosounder and the side-scan sonar during Gdansk Bay sounding.
Źródło:
Polish Maritime Research; 2017, 4; 35-41
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the corrosion tester in corrosion tests using the acoustic emission method
Autorzy:
Emilianowicz, Krzysztof
Supernak, Milena
Ossowska, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/32912355.pdf
Data publikacji:
2022
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
corrosion
hull steels
acoustic emission
corrosion tester
Opis:
The article presents an innovative method of corrosion tests using the acoustic emission method and the corrosion tester. The problem of corrosion occurring in ballast tanks and tanks carrying petroleum products is discussed. The acoustic method is presented which, due to the use of a unique corrosion tester, is used to monitor the course of corrosion processes in steel. The principle of operation of the corrosion tester, its construction and its use in Non Destructive Testing (NDT) are described in detail. Corrosion test results, obtained with the use of a corrosion tester, are presented. An analysis and a short discussion of the obtained results are given. The results of both the acoustic and metallographic tests prove the possibility of detecting material damage occurring during the operation of the corrosion tester, allowing determination of the course and type of corrosion damage.
Źródło:
Polish Maritime Research; 2022, 3; 167-175
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Results of acoustic emission tests of corrosion protection degree of ship steel tanks covered by means of protective coatings. (Phase I)
Autorzy:
Bugłacki, H.
Eichert, P.
Powiązania:
https://bibliotekanauki.pl/articles/963385.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
protective coatings
ship tanks
corrosion
acoustic emission
Opis:
This paper presents methods and results of the 1st series of tests of acoustic emission (AE) signals, aimed at assessing degree of corrosion protection of a tank made of hull structural steel, protected by means of a protective coating combined from polyurethane layer and concrete filler. The tests were carried out in compliance with a method specially elaborated for application to the work in question. In the method were used requirements of the standards in force, as well as experience gained during realization of the research project CORRSHIP, included in 5th Frame Program of European Union. The application of the AE method to detect and localize corrosion sources during exposure of specimens to corrosive mixture confirmed its high usefulness for the carried-out tests on corrosion protection effectiveness of new types of protective coatings.
Źródło:
Polish Maritime Research; 2008, S 1; 35-41
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Searching for objects under the sea bed by the nonlinear acoustics methods
Autorzy:
Kozaczka, E.
Powiązania:
https://bibliotekanauki.pl/articles/258470.pdf
Data publikacji:
2007
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
sea exploration by acoustic methods – nonlinear acoustics
parametric sources
Opis:
Paper presents rules of producing sources of the parametric acoustic waves as an effect of the propagation of two parallel acoustic beams. Wave is generated in the mutual impact area, with a frequency equal to the difference of the frequencies of waves radiated from the original sources. This principle is a base of the construction of parametric sonars with very narrow directional characteristics and relatively low wave frequency. Moreover, the directional characteristics do not have side lobes - a drawback of the classic sonars. Parametric sonars are a good tool of detecting objects on the sea bed and particularly those buried in the sea bed. The use of parametric sonars in searches for objects such as mines or pieces of archeological value is a modern way of carrying out directed exploration of the sea bed.
Źródło:
Polish Maritime Research; 2007, S 2; 25-26
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of acoustic field for a parametric focusing source using the spheroidal beam equation
Autorzy:
Yu, L.
Li, J.
Shi, C.
Powiązania:
https://bibliotekanauki.pl/articles/258564.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
parametric focusing source
difference frequency wave
SBE
acoustic field
Opis:
A theoretical model of acoustic field for a parametric focusing source on concave spherical surface is proposed. In this model, the source boundary conditions of the Spheroidal Beam Equation (SBE) for difference frequency wave excitation were studied. Propagation curves and beam patterns for difference frequency component of the acoustic field are compared with those obtained for Khokhlov-Zabolotskaya-Kuznetsov (KZK) model. The results demonstrate that the focused parametric model of SBE is good valid for a large aperture angle in the strongly focused acoustic field. It is also investigated that high directivity and good focal ability with the decreasing of downshift ratio and the increasing of half-aperture angle for the focused parametric model of SBE.
Źródło:
Polish Maritime Research; 2015, S 1; 43-47
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new low SNR underwater acoustic signal classification method based on intrinsic modal features maintaining dimensionality reduction
Autorzy:
Ju, Yang
Wei, Zhengxian
Li, Huangfu
Feng, Xiao
Powiązania:
https://bibliotekanauki.pl/articles/259300.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
acoustic
low SNR
signal classification
feature maintain
dimension reduction
Opis:
The classification of low signal-to-noise ratio (SNR) underwater acoustic signals in complex acoustic environments and increasingly small target radiation noise is a hot research topic. . This paper proposes a new method for signal processing—low SNR underwater acoustic signal classification method (LSUASC)—based on intrinsic modal features maintaining dimensionality reduction. Using the LSUASC method, the underwater acoustic signal was first transformed with the Hilbert-Huang Transform (HHT) and the intrinsic mode was extracted. the intrinsic mode was then transformed into a corresponding Mel-frequency cepstrum coefficient (MFCC) to form a multidimensional feature vector of the low SNR acoustic signal. Next, a semi-supervised fuzzy rough Laplacian Eigenmap (SSFRLE) method was proposed to perform manifold dimension reduction (local sparse and discrete features of underwater acoustic signals can be maintained in the dimension reduction process) and principal component analysis (PCA) was adopted in the proces of dimension reduction to define the reduced dimension adaptively. Finally, Fuzzy C-Means (FCMs), which are able to classify data with weak features was adopted to cluster the signal features after dimensionality reduction. The experimental results presented here show that the LSUASC method is able to classify low SNR underwater acoustic signals with high accuracy.
Źródło:
Polish Maritime Research; 2020, 2; 187-198
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Processing data on sea bottom structure obtained by means of the parametric sounding
Autorzy:
Kozaczka, E.
Grelowska, G.
Kozaczka, S.
Szymczak, W.
Powiązania:
https://bibliotekanauki.pl/articles/259876.pdf
Data publikacji:
2012
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
sea bottom acoustic
sub-bottom profiler
sea bed structure
Opis:
The aim of the paper is to analyze data obtained during sounding the Gdansk Bay sea bed by means of the parametric echo-sounder. The accuracy of the sea bottom structure investigation needs correct configuration of research equipment and proper calibration of peripheral devices (GPS, heading sensor, MRU-Z motion sensor and navigation instruments which provide necessary data to bathymetrical measurement system, enabling its work with full capability. The parametric sub-bottom profiler delivers two types of data which include different information: envelope and pure echo signal sampled without processing. The first is used to present echograms in real time and the second one is stored during sounding and the obtained data can be analyzed by using post-processing software. Differences in the results are presented and discussed. And, are described also criteria taken into account during determination of the measurement areas and selection of different configurations of the software according to the information to be obtained from trials. Complementary information can be achieved from processing the data by means of the procedures offered by Matlab software, which allows for a clear 3D presentation of the results. The consideration are illustrated by echograms taken in the natural conditions.
Źródło:
Polish Maritime Research; 2012, 4; 3-10
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monitoring of underdeck corrosion by using acoustic emission method
Autorzy:
Emilianowicz, K.
Powiązania:
https://bibliotekanauki.pl/articles/260546.pdf
Data publikacji:
2014
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
underdeck corrosion
acoustic emission (AE)
corrosion tester
marine units
Opis:
This paper presents first short characteristics of underdeck corrosion process as well as a problem of its monitoring. Next is described an acoustic emission (AE) method elaborated by Department of Ship Technology, Quality Systems and Material Engineering, Gdańsk University of Technology in cooperation with partners of CORFAT project realized within 7th EU Frame Program. Further are presented short characteristics of the emission process, used measuring instrumentation of Vallen Systeme GmbH, as well as TESTER, corrosion testing device, and a corrosion solution used in the tests. Finally, results of the tests performed on selected marine units, are presented. 1*GUT - Gdańsk University of Technology 2*TÜV- Austria 3*TESTER - a device used for simulation of corrosion processes without destruction of tested material surface. 4*Corrosive solution - a solution which catalizes corrosion processes in the tester 5*SMW S.A.- Naval Shipyard Co.
Źródło:
Polish Maritime Research; 2014, 1; 54-61
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical model of acoustic wave propagation in shallow water
Autorzy:
Kozaczka, E.
Grelowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/258460.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
shallow water acoustics
propagation of acoustic waves in water layer
Opis:
The work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “deformed” by different phenomena. The acoustic field distribution in the real shallow sea is affected not only by multiple reflections, but also by stochastic changes in the free surface shape, and statistical changes in the seabed shape and impedance. The paper discusses fundamental problems of modal sound propagation in the water layer over different types of bottom sediments. The basic task in this case was to determine the acoustic pressure level as a function of distance and depth. The results of the conducted investigation can be useful in indirect determination of the type of bottom.
Źródło:
Polish Maritime Research; 2017, 2; 48-55
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The imaging of Gdansk Bay seabed by using side sonar
Autorzy:
Grelowska, G.
Kozaczka, E.
Witos-Okrasińska, D.
Szymczak, W.
Powiązania:
https://bibliotekanauki.pl/articles/259025.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
Gdańsk Bay seabed
side sonar
hydro-acoustic systems in waters
Opis:
This paper is mainly aimed at presentation of an impact of environmental conditions on imaging accuracy by using hydro-acoustic systems in waters of a high non-uniformity of spatial distribution of hydrological parameters. Impact of refraction on erroneous estimation of range, in case of wave radiation into water under a large angle, like in side sonars or multi-beam echo-sounders, is especially important. In this paper seasonal changes in sound speed and its impact on acoustic beam refraction is discussed. And, examples which illustrate errors in determination of side sonar range occurred during last investigations carried out in Gdansk Bay waters are presented.
Źródło:
Polish Maritime Research; 2018, S 1; 111-118
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of seasonal acoustic properties of sea water in selected waters of the southern Baltic
Autorzy:
Grelowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/259798.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
sound propagation in sea water
acoustic climate of Baltic Sea
Opis:
Climate Research of the globe is a current task, in particular to confirm the general hypothesis of global warming associated with an increase in average temperature. The sea acoustic climate is derived from the concept of climate and refers to the conditions of propagation of acoustic waves in a particular basin. In this paper, the results of systematic measurements of temperature, salinity and velocity distributions of sound in the area of the southern Baltic will be present. The focus will be on the results of extensive measurements carried out „in situ” in particular.
Źródło:
Polish Maritime Research; 2016, 1; 25-30
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Underwater target direction of arrival estimation by small acoustic sensor array based on sparse bayesian learning
Autorzy:
Wang, B.
He, C.
Powiązania:
https://bibliotekanauki.pl/articles/260588.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
DOA
underwater acoustic signal processing
sparse Bayesian learning
temporally correlated source
Opis:
Assuming independently but identically distributed sources, the traditional DOA (direction of arrival) estimation method of underwater acoustic target normally has poor estimation performance and provides inaccurate estimation results. To solve this problem, a new high-accuracy DOA algorithm based on sparse Bayesian learning algorithm is proposed in terms of temporally correlated source vectors. In novel method, we regarded underwater acoustic source as a first-order auto-regressive process. And then we used the new algorithm of multi-vector SBL to reconstruct the signal spatial spectrum. Then we used the CS-MMV model to estimate the DOA. The experiment results have shown the novel algorithm has a higher spatial resolution and estimation accuracy than other DOA algorithms in the cases of less array element space and less snapshots.
Źródło:
Polish Maritime Research; 2017, S 2; 95-102
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of low-sidelobe beampattern controlling methods for acoustic transmitting array of underwater vehicles
Autorzy:
He, Z.
Shi, Q.
Wu, S.
Powiązania:
https://bibliotekanauki.pl/articles/258624.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
underwater unmanned vehicles
detecting and positioning
acoustic transducer
complex array
low-sidelobe beamforming
Opis:
In underwater unmanned vehicles, complex acoustic transducer arrays are always used to transmitting sound waves to detect and position underwater targets. Two methods of obtaining low-sidelobe transmitting beampatterns for acoustic transmitting arrays of underwater vehicles are investigated. The first method is the boundary element model optimization method which used the boundary element theory together with the optimization method to calculate the driving voltage weighting vector of the array. The second method is the measured receiving array manifold vector optimization method which used the measured receiving array manifold vectors and optimization method to calculate the weighting vector. Both methods can take into account the baffle effect and mutual interactions among elements of complex acoustic arrays. Computer simulation together with experiments are carried out for typical complex arrays. The results agree well and show that the two methods are both able to obtain a lower sidelobe transmitting beampattern than the conventional beamforming method, and the source level for each transmitting beam is maximized in constraint of the maximum driving voltage of array elements being constant. The effect of the second method performs even better than that of the first method, which is more suitable for practical application. The methods are very useful for the improvement of detecting and positioning capability of underwater unmanned vehicles.
Źródło:
Polish Maritime Research; 2017, S 2; 103-110
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the modified echo highlight model for underwater vehicles with combined structures
Autorzy:
Xie, Xin
Liu, Fanghua
Jin, Guangwen
Liu, Jinwei
Xu, Cong
Peng, Zilong
Powiązania:
https://bibliotekanauki.pl/articles/34609383.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
modified highlight model
wedge-shaped convex structure
piecewise synthesis method
acoustic scattering calculation software
Opis:
The highlight model is widely used as a simple and convenient method in the radar field but its accuracy is not high. Based on the traditional highlight model, the algorithm has been improved to address the acoustic scattering problems of underwater vehicles with more complex line shapes. The basic idea is to partition the model into micro-bodies to calculate the scattered sound pressure, consider the phase interference of each part, and then synthesise the scattered sound pressure to approximate the target’s actual shape. A computational model of the wedge-shaped convex structure on the back of the underwater vehicles is developed using a highlight model of a trapezoidal plate. The results of the calculations using the highlight model approach are consistent with those of the planar element method. Utilising the modified highlight model method, the accuracy of acoustic scattering characteristics calculations for the stern and overall structures of underwater vehicles has proven satisfactory. Finally, fast acoustic scattering prediction software is developed for underwater vehicles, enabling the calculation of the acoustic scattering characteristics for individual structures, combined structures, and coated silent tiles. This software provides algorithmic support for the fast prediction of the acoustic stealth performance of underwater vehicles.
Źródło:
Polish Maritime Research; 2023, 3; 163-173
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł

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