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Wyświetlanie 1-15 z 25
Tytuł:
Investigation of the pulse reflected from bottom sediments
Autorzy:
Nowak, Ł.
Szymczak, W.
Powiązania:
https://bibliotekanauki.pl/articles/332780.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
bottom sediments
pulse reflected
hydroacoustics
Opis:
The paper describes method of determining time proceeding of the echo pulse arising as an effect of reflection of sampling pulse given with the known form from layered sea bottom. The main goal of presented model is to afford theoretical data that could be used as a point of reference for the experimental data obtained with SES 2000 Standard parametric echosounder. Basic formulas, computation algorithm with its implementation in Matlab language and examples of obtained results are described. Numerical simulations results are compared with experimental data. The laboratory station enabling computing acoustic impedance of sediments and parameters of sampling and echo pulse in different distances from antenna is presented.
Źródło:
Hydroacoustics; 2009, 12; 159-166
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sensitivity of echo envelope fractal dimension to bottom type and bottom depth - numerical results
Autorzy:
Łubniewski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/332051.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
acoustic
seafloor
hydroacoustics
Opis:
The presented results are a part of those obtained within the author's latest work on application of normal incidence methods in acoustic seafloor characterisation. The work included both theoretical and experimental studies on selection of appropriate methods of seafloor echo processing and feature extraction for characterisation of the bottom type, especially, the study of the usefulness of several echo parameters like fractal dimension or statistical moments of the echo envelope. In this paper, the simulation results of the echo envelope fractal dimension dependence on bottom type and bottom depth are presented. They show that to same extent, fractal dimension of an echo may be useful for bottom identification even in a case of varying depth, however, more detailed, theoretical as well as experimental studies are needed.
Źródło:
Hydroacoustics; 2003, 6; 195-198
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some methods of the sea bottom recognition
Autorzy:
Grelowska, G.
Kozaczka, S.
Szymczak, W.
Powiązania:
https://bibliotekanauki.pl/articles/332558.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
sea bottom recognition
Gdansk Gulf region
sonar
Opis:
Sea bottom structure recognition nowadays is a matter of great interest due to huge spectrum of potential applications, such as a hydrography, military oceanography, marine geosciences, offshore industry, environmental protection and many others. For that reason a great variety of tools and techniques for sea bottom measurements and modeling is developed. However, each technique leads to specific bottom images and allows to determine only few characteristics of examined area. In the paper are presented experimental results collected in the Gdansk Gulf region obtained by means of three technique: wide side sonar, parametric sonar and multi-beam sonar.
Źródło:
Hydroacoustics; 2009, 12; 69-76
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of bottom sediment stratification
Autorzy:
Grelowska, G.
Kozaczka, E.
Powiązania:
https://bibliotekanauki.pl/articles/332163.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The main goal of this paper is to find a method to assess remotely the type of sediments on the basis of the signal received using the parametric echosounder. The images of the sea bottom sediments taken by a parametric echosounder show the fine structure of the upper layer of the bottom sediments. The depth of penetration depends on the type of sediment, in fact on the attenuation of acoustic wave. In the paper the method of distinguishing the sediment layer basing on interpretation the received bottom signal is proposed. The knowledge on acoustic parameters of different type of sediments obtained in laboratory condition or using the literature data, allows to predict the composition of upper layer of the bottom. The considerations are illustrated by the results recorded from the bottom of the Gulf of Gdansk.
Źródło:
Hydroacoustics; 2014, 17; 93-103
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of sea bottom using bézier pieces
Autorzy:
Makar, A.
Powiązania:
https://bibliotekanauki.pl/articles/331993.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
In the article the essence of creating Bézier piece, determination its points, degree elevation and division have been shown. These issues are essential during creation the digital terrain model DTM. For creation the sea bottom model bathymetric surveys of Slupsk Bank have been used. The visualization of sea bottom with detected underwater object recorded by multibeam echosounder using Bézier pieces has been presented.
Źródło:
Hydroacoustics; 2010, 13; 183-190
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:
Modeling of sea bottom using uniform rectangular Bézier pieces
Autorzy:
Makar, A.
Powiązania:
https://bibliotekanauki.pl/articles/331828.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
In the article the essence of uniform rectangular Bézier pieces have been shown. These issues are essential during creation the digital terrain model DTM. For creation the bottom model bathymetric surveys of Motlawa River have been used. The visualization of the bottom using uniform rectangular Bézier pieces has been presented.
Źródło:
Hydroacoustics; 2011, 14; 143-148
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Artificial neural networks for shape modeling of sea bottom
Autorzy:
Balicki, J.
Powiązania:
https://bibliotekanauki.pl/articles/332457.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Artificial neural networks are applied for approximation and interpolation of function with multiple variables. Because of concurrent processing of data by neurons, fhis approach can be seen as promising alternate for standard algorithms. From these reasons, the analysis of capabilities for some models of neural networks has been carried out in the purpose for modeling the shape of sea bottom. The feed-forward multi-layer networks with different transfer functions have been tested. These networks have been trained by backpropagation algorithm and its versions with some improvements. Moreover, the gradient optimization technique by Levenberg-Marquardt has been applied. Finally, for determination of the depth in a point of the water area the two-layer network with the hidden layer of the radial neurons has been proposed.
Źródło:
Hydroacoustics; 2007, 10; 1-8
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of selected classifiers in a sea-bottom recognition task
Autorzy:
Komendarczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/331784.pdf
Data publikacji:
1997
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
This paper presents a test of three following classifiers: minimum-distance classifier, feed-forward neural network with backpropagation learning scheme and neuro-fuzzy classifier based on NEFCLASS architecture. They have been applied to the sea bottom type classification task over different input spaces. The experiment proved high efficiency of the minimum-distance classifier and the neural network, NEFCLASS performance had been rather poor. Generalization properties of those classifiers are also investigated. Additional conclusions concerning classifiers topology are presented.
Źródło:
Hydroacoustics; 1997, 1; 125-130
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wideband Synthetic Aperture Mapping of the sea bottom
Autorzy:
Zakharia, M. E.
Châtillon, J.
Powiązania:
https://bibliotekanauki.pl/articles/332223.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Seabed survey using wideband synthetic aperture sonar can provide high resolution images and maps (a cubic meter voxel at a few kilometres range) using a reasonable array size (2 metres) and a rather low frequency range (6-12 kHz). A low frequency profofype has been constructed in the frame of the MAST profect SAMI "Synthetic Aperture Mapping and Imaging". A large amount of experimental data was obtained at sea and stored for further processing. The paper will show some of these results. It will display bofh synthetic images and 3D maps.
Źródło:
Hydroacoustics; 1999, 2; 121-126
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:
The primary sources of ship noise observed on the bottom of sea
Autorzy:
Listewnik, K.
Powiązania:
https://bibliotekanauki.pl/articles/331932.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The paper presents the experimental research associated with the spatial distribution of acoustic energy generated by moving ship into the shallow water. Moreover, the paper present the methodology of determination of acoustics energy from the main mechanisms of ship into the water environment. For that purpose the research of noise spatial distribution of the ship were conducted along the hydroacoustic field. This research allowed to determine ship signature spatial distribution of chosen main mechanisms on the bottom of sea.
Źródło:
Hydroacoustics; 2010, 13; 163-170
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
System for bottom typing with geographical context mapping
Autorzy:
Moszyński, M.
Partyka, A.
Stepnowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/332157.pdf
Data publikacji:
1997
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The paper presents a system of bottom classification with geographical context mapping. It combines two previously developed subsystems, viz.: EchoBase - a portable dynamic Geographical Information System and Visual Bottom Typer (VBT) System. A newly developed version of the system was supplemented with interprocess communications mechanisms which allow transfer of data from one system to the other. These two software packages can run concurrently in multitasking. The MS Windows operating environment provides a mapping possibility of a classified sea bed type with an on-line geographical visualization on the nautical map. Both systems were presented separately in previous Symposiums' proceedings.
Źródło:
Hydroacoustics; 1997, 1; 135-140
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial distributions of acoustic field scattered at the sea bottom-numerical model
Autorzy:
Tęgowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/332620.pdf
Data publikacji:
1997
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The results of the numerical simulation of acoustic wave scattering from rough and attenuating sea bottom are presented. Seattering is studied using ray theory with the main geometry of model taken from Novarini and Caruthers. The distribution of rough surface heights together with bottom acoustical parameters determine the scattered acoustical field properties. Different bottom types with various acoustical parameters have been used in numerical calculations in order to examine the influence of phase shift of reflected signal on scattered acoustical field. Simulation technique was made for surfaces with normal distribution of heights and standard deviation of the surface elevation, 0.01 m. Spatial distribution of the scattered field parameters was determined. Results of calculations for frequencies between 5 and 100 kHz and various bottom parameters are compared.
Źródło:
Hydroacoustics; 1997, 1; 141-146
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractal laws of sound backscattering by sea surface and bottom
Autorzy:
Lyamshev, L. M.
Stepnowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/331953.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
It is demonstrated that the known empirical frequency-angle dependence that characterizes the intensity of high-frequency backscattering of sound by a rough sea surface and is obtained on the basis of generalization of results of many experiments conducted by various researchers under different conditions and in different sea regions has a fractal character. High-frequency backscattering of sound by the sea bottom is also characterized by fractal laws in a broad range of frequency and spatial scales.
Źródło:
Hydroacoustics; 2001, 4; 143-148
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
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