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Wyszukujesz frazę "Łubniewski, Z." wg kryterium: Autor


Tytuł:
A Novel approach to bottom scattering using a narrow acoustic beam
Autorzy:
Zieliński, A.
Tegowski, J.
Lubniewski, Z.
Demkowicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/332113.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The acoustic response of the ocean bottom to a probing pulse is a complex and complicated process. This process is influenced by with the form of an acoustic transmitting/receiving beam and by the physical processes involved in sound scattering from the surface and the volume of the ocean bottom. The complexities of these phenomena often obscure an intuitive understanding of the underlying principles of echo formation and its reception. In this paper, we propose a simplistic model for this complex process using filter theory. The bottom is represented as a surface reflector with an acoustic wave front sweeping over it with time-varying velocity. The impulse response of a smooth flat bottom is characteristic of a low pass-filter that will greatly attenuate the impinging high frequency pulse. On the other hand, bottom undulations will modulate the reflected signal such that it can be represented by the impulse response of a band-pass filter. The received echo can be represented as the response of such filter to a high frequency pulse. The characteristics and amplitude of the echo are dependent on frequency spectrum overlap between the transmitted pulse spectrum and the filter frequency response. In the paper, we discuss several cases of interest with the intent to provide a solid intuitive understanding of the echo formation from the system point of view.
Źródło:
Hydroacoustics; 2004, 7; 253-258
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of some echo parameters to the seabed classification - methodological analysis
Autorzy:
Tęgowski, J.
Łubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/332378.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The paper presents the methodological analysis of acoustical seabed classification procedure, which aim is to define the most appropriate bottom echo parameters as an input set. Several acoustical and statistical features of echo envelope were compared with morphological features of bottom sediments and a set of parameters was proposed: integral backscattering strength, time of reverberation, radius of autocorrelation, fractal dimension, moment of inertia, and skewness. It was shown using real echoes from seafloor, that this set may be a good descriptor of sea bottom sediments and may be used in classification procedures. In addition, the spatial distribution of echo skewness within Polish Economical Zone of Baltic Sea was presented as an example and compared with sediments allocation map.
Źródło:
Hydroacoustics; 2001, 4; 237-240
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractal characterisation of 30 kHz echoes from southern Baltic bottom
Autorzy:
Tęgowski, J.
Łubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/331844.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The fractal dimension of 30 kHz echo envelope is used for characterise the bottom sediment type in Southern Baltic Sea. Two methods of the echo waveform fractal dimension calculation were applied: the autocorrelation function log-log slope method and the power spectrum log-log slope method. The results are presented and compared. They show that fractal dimension of echo envelope describes well the bottom sediments morphology and may be used as a significant descriptor in the remote sea bed classification procedures.
Źródło:
Hydroacoustics; 2000, 3; 15-18
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel method for archiving multibeam sonar data with emphasis on efficient record size reduction and storage
Autorzy:
Moszynski, M.
Chybicki, A.
Kulawiak, M.
Lubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/260572.pdf
Data publikacji:
2013
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
sonar
compression
storage
reduction
efficiency
Opis:
Over the past few years considerable advances in sonar technology, spatial positioning capabilities and computer processing power have lead to significant improvements in mapping, imaging and technologies of seafloor exploration. Recently, modern multibeam echosounder systems (MBES) capable of recording backscatter data for the whole water column, not just for the seabed, have become available thus providing data allowing for visualization and analysis of objects other than the seabed such as single fish, fish schools or pollution. Unlike bathymetric sonars, which only capture the seafloor, multibeam systems produce very large amounts of data during surveys. Because of this, storing the data collected during hydrographic or scientific cruises becomes a crucial problem. In this context, the paper proposes a new approach for efficient reduction and storage of MBES records. The results of a sample implementation of the algorithm being tested on several different sets of MBES data are also discussed.
Źródło:
Polish Maritime Research; 2013, 1; 77-86
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-frequency analysis of seabed echoes using wavelet transform
Autorzy:
Moszyński, M.
Stepnowski, A.
Łubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/332256.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The methods based on analysis of boftom backscatter data from a single-beam echosounder have achieved special attention in the seabed identification problem. due to their simplicity over ofher more sophisticated acoustic techniques like side scan sonar or multibeam surveys. The majority of these methods analyses the scattering phenomena mostly in time domain (echo envelope). However, the frequency echo components carry concurrent information, which can be also used in boftom characterisation. The paper proposes the time-frequency approach to the boftom characterisation and presents the application of Wigner- Ville Distribution and wavelet transform of boftom backscatter data. The examples of continuous and discrete wavelet transforms of actual echo envelopes received at three boftom types for three different operating frequencies (38, 120 and 420 kHz) are shown. Their characteristic features are compared and parameters for classification schemes are proposed. The results of classification procedure are good with comparison with those of ofher simple acoustic methods.
Źródło:
Hydroacoustics; 1999, 2; 85-90
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reconstruction of 3D shape from sidescan sonar images using shape from shading technique
Autorzy:
Moszyński, M.
Bikonis, K.
Łubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/332701.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Side scan sonar (SSS) is one of the most widely used imaging systems in the underwater environment. It is relatively cheap and easy to deploy in comparison with more powerful sensors like multibeam echosounder or synthetic aperture sonar. Although, the SSS does not provide directly the seafloor bathymetry measurements. Its outputs are usually in a form of grey level acoustic images of seafloor. However, the analysis of such images performed by human eye allows creating semi-spatial impressions on seafloor relief and morphology. The 3D shape reconstruction from 2D images using SFS approach is one of classical problems in computer vision. In the paper, the method based on Shape From Shading (SFS) technique for SSS images processing is presented. The 3D seafloor relief is reconstructed using the information from both the currently processed and previous ping. The seafloor backscattering coefficient dependence on an incident angle, which is needed in the applied SFS algorithm scheme, is being estimated in the experimental way, i.e. by analysis of SSS image contents for the flat seabed region.
Źródło:
Hydroacoustics; 2013, 16; 181-188
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of inverse filtering techniques in the sea bottom recognition
Autorzy:
Łubniewski, Z.
Moszyński, M.
Stepnowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332346.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The paper presents the newly developed approach to the sea bottom recognition and identification, which uses inverse filtering techniques to extract bottom scattering properties from a single-beam echosounder signal. Using simple physical model, the developed inverting procedure allows to remove the influence of pulse shape, beam pattern and model geometry upon the backscattered echo. 11permits to obtain the seabed impulse response which is directly related to the function describing the angular dependence of bottom reverberation coefficient. Various direct and iterative inverse methods can be applied to the mentioned problem. The results of testing the method using echoes from several bottom types are in agreement with the predictions of theoretical models. Moreover, the proposed bottom classification procedure uses simple parameters of deconvolved function and the obtained classification results are better than those of ofher bottom identification methods of normal incidence.
Źródło:
Hydroacoustics; 1999, 2; 95-100
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparision of two algorithms of evaluating fractal dimension for sea bottom typing
Autorzy:
Łubniewski, Z.
Kozicki, S.
Stepnowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332344.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The fractal dimension of received echo envelope is a useful parameter in a sea bottom classification procedure. As fractal structure of bottom is believed to transfer onto the shape of echo envelope, fractal dimension may describe properly some physical features of seabed, as surface roughness or complexity of layered structure. The paper presents and compares the results of two methods of fractal dimension calculation from echo envelope given as finite set of discrete values. The first method evaluates box dimension and the second is based on the relation between fractal dimension and Lipschitz exponent, which describes some properties of autocorrelation junction of investigated signal. The obtained results show that at least one type of fractal dimension method may be useful in a sea bottom recognition task.
Źródło:
Hydroacoustics; 1999, 2; 107-112
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maritime awareness and emergency management real time system using remotely accessible GIS technology
Autorzy:
Łubniewski, Z.
Partyka, A.
Stepnowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332721.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The paper concerns the concept of the application of the latest achievements in both information technology and remote sensing, including underwater acoustic sensors, for maritime awareness and emergency management supporting in a case of hazard of a different kind, e.g. terrorism, pollution and ecological catastrophes, or natural disasters. The real-time, remotely accessible marine GIS is dedicated for instantaneous integration, processing and multi aspect visualisation, in a form of time variable views and maps, of the data acquired by various types of sensors. The paper presents the prototype application of the marine GIS for remotely accessible, instantaneous detection, localisation and monitoring of sea water pollution aggregations, e.g. oil spills, discharge material plumes etc. The developed system is also capable of performing the instantaneous prediction of the pollutants' behaviour, i.e. the dislocation and spreading of an oil spill, in the nearest future, using the relevant physical models. The system utilises the SQL database for data storage and the SVG language for geographical objects remote presentation, and requires only the WWW browser and SVG viewer on the client side.
Źródło:
Hydroacoustics; 2005, 8; 105-110
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling the seafloor 3D relief and its reconstruction from multibeam sonar data
Autorzy:
Łubniewski, Z.
Moszyński, M.
Powiązania:
https://bibliotekanauki.pl/articles/331622.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The simple, real-time procedure for seafloor relief reconstruction and simultaneous seabed type identification using echo data from hypothetical multibeam sonar system was proposed. The algorithm was tested using artificially generated relief and seabed type data. In the first stage, 3D surface of seafloor was generated, using the inverse Fourier transformation of the 2D spatial frequency spectrum of power law form. In the second stage, the generation. of the set of multibeam sonar data, which simulated echoes collected from seabed, was performed with account for the distances from transducer to particular surface elements, scattering coefficient and the angles of insonification. Finally, the spatial form of seabed was reconstructed using the simulated data, while bottom type was identified simultaneously using estimated angular dependence of backscattering coefficient. The obtained results showed the good performance of the proposed reconstruction procedure for artificial data and suggested verification of the algorithm using real data.
Źródło:
Hydroacoustics; 2001, 4; 153-156
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelowanie odpowiedzi impulsowej dla rozpraszania wstecznego dna morskiego
Modelling of the impulse response for backscattering from seafloor
Autorzy:
Łubniewski, Z.
Moszyński, M.
Stepnowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332215.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The modelling of surface and volume backscattering of a single-beam echosounder signals on sea fioor using impulse response approach is presented. Kirchhoff (tangent plane) approximation is used in surface scattering modelling for approximately fiat sea bottom and smal! perturbation theory is applied to describe the volume backscattering. The influence of bottom physical features as well as the system parameters (operating frequency, beamwidth) on the shape of the sea bed impulse response and echo waveform is investigated. The results have revealed the differences for particular cases of bottom and acoustic system 's parameters and they are important for validation of newly developed algorithms of echo signals processing for bottom classification.
Źródło:
Hydroacoustics; 2000, 3; 35-38
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulations of acoustic backscattering on fractally corrugated Seabed surface
Autorzy:
Łubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/332288.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The numerical simulations of echosaunder signals scattering by fractally corrugated sea bed surface are presented. In particular, the relations between fractal dimension, describing the large scale roughness of sea bottom, and received echo envelope shape, were investigated. The fractal large scale relief of seabed suiface was generated assuming the power law form of the spatial frequency power spectrum, with exponent related to fractal dimension, and subsequently applying the two dimensional inverse FFT algorithm. In the secand stage, the bottom echo waveform was numerically modelled as an incoherent sum of coruributing echoes from all surface elements. For each element, the echo amplitude was calculated assuming the form of angular dependence of bottom backscattering coefficient for smal! scale roughness. The obtained results of simulations have revealed same conditions for the transferring of the seabed surface fractal structure onto the shape of echo wavefonn.
Źródło:
Hydroacoustics; 2000, 3; 25-28
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On algorithm details in multibeam seafloor classification
Autorzy:
Łubniewski, Z.
Sęk, D.
Powiązania:
https://bibliotekanauki.pl/articles/331668.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
seafloor classification
multibeam sonar
sonar data processing
Opis:
Remote sensing of the seafloor constitutes an important topic in exploration, management, protection and other investigations of the marine environment. In the paper, a combined approach to seafloor characterisation is presented. It relies on calculation of several descriptors related to seabed type using three different types of multibeam sonar data obtained during seafloor sensing, viz.: 1) the grey-level sonar images (echograms) of the seabed, 2) the 3D model of the seabed surface which consists of bathymetric data, 3) the set of time domain bottom echo envelopes received in the consecutive sonar beams. The proposed methodology has been tested using field data records acquired from several bottom types in the Southern Baltic Sea. Using the examples of particular parameters, the influence on the specific manner and details regarding their calculation, i.e. the size of the applied current local window to a sonar image, on the obtained classification performance, is discussed.
Źródło:
Hydroacoustics; 2017, 20; 113-120
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sea bottom typing using fractal dimension
Autorzy:
Łubniewski, Z.
Stepnowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332284.pdf
Data publikacji:
1997
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The article presents an attempt to apply elements of fractal analysis for the purpose of sea bottom typing. The fractal dimension was calculated as box dimension for sampled envelopes of echo signals from four types of sea bottom recorded during mobile acoustic surveys carried out in Lake Washington. The results obtained show that the simple method applied can be used for on board sea bed recognition in real time with accuracy similar to that of other methods.
Źródło:
Hydroacoustics; 1997, 1; 131-134
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sea floor classification using multibeam sonar
Autorzy:
Łubniewski, Z.
Chybicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/332796.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
sea floor classification
multibeam sonar
hydroacoustics
Opis:
The paper presents the method of seabed identification and classification using multibeam sonar echoes. The proposed approach is based on calculation of a set of parameters of an echo envelope. The parameters are extracted for each consecutive beam allowing the estimation of their dependence on the seafloor incident angle, and then the relation between seabed type and calculated echo parameters and its angular dependence is investigated. The paper concerns the experiment which has been carried out in Gdansk Bay in November 2008, and some comparisons of the results with those obtained during previous experiment in September 2007. The results for several bottom types are presented and discussed. It was confirmed that the information extracted from multibeam seafloor sensing data, e.g. "water column" recordings, may be useful in seafloor characterisation.
Źródło:
Hydroacoustics; 2009, 12; 127-132
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł

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