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1

Study of seasonal acoustic properties of sea water in selected waters of the southern Baltic

100%
Grelowska G.
Polish Maritime Research
|
2016
|
tom 23
|
nr 1
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
2

Autonomous platform to protect maritime infrastructure facilities

63%
Kozaczka E., Grelowska G.
Polish Maritime Research
|
2019
|
tom 26
|
nr 4
Problems regarding the security of maritime infrastructure, especially harbours and offshore infrastructure, are currently a very hot topic. Due to these problems, there are some research projects in which the main goal is to decrease the gap and improve the methods of observation in the chosen area, for both in-air and underwater areas. The main goal of the paper is to show a new complex system for improving the security of the maritime infrastructure by means of many methods of observation – such as thermovision, optical devices, and radar systems – generally by means of an electromagnetic wave as a carrier of information in the air and acoustical methods in water. The system can be applied to the protection of maritime infrastructure as well as the coastal zone
3

Propagation of ship-generated noise in shallow sea

63%
Kozaczka E., Grelowska G.
Polish Maritime Research
|
2018
|
tom 25
|
nr 2
Contamination of sea environment by noise and any energy radiated to water constitutes today a problem to which more and more attention is paid, in view, a.o., of consequences of an impact of these factors onto marine fauna. European Union has introduced a directive by which EU countries are made responsible to undertake efforts aimed at reaching a good envirenmental status of European seas by 2020. A main source of underwater noise is sea transport of any kind. Propagation of underwater acoustic disturbances in the Baltic Sea highly differs from the course of the phenomenon in a deep sea. Model of spherical propagation cannot be applied to this case in view of water environment limitation by seabed and free water surface, i.e. a reduction of the problem to wave propagation in a water layer of the depth comparable with acoustic wave length. This paper is aimed at demonstration of possible assessment of range of acoustic disturbances generated by a ship sailing in shallow sea, by using a method described in the work [13]. The research was made on the basis of results of own measurements of underwater noise produced by ships in the Gdansk Bay area. An important factor which decIdes on a range of underwater disturbances is a kind of seabed sediments. In this paper there are presented results of numerical investigations based on real data dealing with noise produced by a selected floating unit (ship) for selected characteristic spectral components. The simulations were conducted for the shallow sea model of definite physical parameters such as acoustic wave propagation velocity, geometrical dimensions (water depth) and seabed acoustic parameters as well
4

Theoretical model of acoustic wave propagation in shallow water

63%
Kozaczka E., Grelowska G.
Polish Maritime Research
|
2017
|
tom 24
|
nr 2
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
5

Forecasting the echo-ranging reach in order to increase operational capacity in the naval defense zone of the Republic of Poland

63%
Grelowska G., Gloza I.
Polish Journal of Environmental Studies
|
2005
|
tom 14
|
nr Suppl.1
Acoustic methods are the most effective in underwater search; nevertheless, their application in the southern Baltic is a far more complex task then under oceanic conditions. The knowledge of acoustic wave propagation under water finds a twofold application in the Navy. Firstly, it serves the purpose of increasing the possibilities of detection, observation and identification of objects moving under water, and secondly, it is used for passive defence by minimising the acoustic field of one’s own vessel. The paper presents results of research on conditions of acoustic wave propagation in the southern Baltic. The characteristics of acoustic climate of the Baltic and its anomalies has been prepared on the basis of echo ranging and hydroacoustic research from 1902-2004. Moreover, the effect of variability of spatial distribution of sound velocity on the propagation of acoustic waves has been shown, which determines the range of hydroacoustic devices and also the hydroacoustic field range of one’s own vessel.
6

Gdansk Bay sea bed sounding and classification of its results

51%
Grelowska G., Kozaczka E., Kozaczka S., Szymczak W.
Polish Maritime Research
|
2013
|
tom 20
|
nr 3
The main goal of this paper is to describe the results of sounding the Gdansk Bay sea bed by using a SES2000 Standard parametric sub-bottom profiler. Quality of data obtained during trials depends inter alia on a proper location of transducer array to reduce influence of pitch, roll and heave motions as well as ship self noise (resulting from bubbles due to propeller and flow around hull, vibration generated by main engine and auxiliary devices). Furthermore, calibration of complementary units such as GPS, heading sensor, MRU-Z motion sensor and navigation devices make sea-bed investigating system capable of working with its whole capability. Results of so prepared surveys have been presented and discussed. They contain also an elaborated map of Gdansk Bay with preliminarily classified sea-bed materials and description of most interesting areas
7

Acoustic imaging of selected areas of Gdansk Bay with the aid of parametric echosounder and side-scan sonar

51%
Grelowska G., Kozaczka E., Szymczak W.
Polish Maritime Research
|
2017
|
tom 24
|
nr 4
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
8

The imaging of Gdansk Bay seabed by using side sonar

51%
Grelowska G., Kozaczka E., Witos-Okrasinska D., Szymczak W.
Polish Maritime Research
|
2018
|
tom 25
|
nr Special Issue S1
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
9

Identification of hydro-acoustic waves emitted from floating units during mooring tests

51%
Kozaczka E., Domagalski J., Grelowska G., Gloza I.
Polish Maritime Research
|
2007
|
tom 14
|
nr 4
Measurements of hydro-acoustic noise emitted from vessels are a.o. a subject of the tests carried out in the control measurement ranges of the Navy. The measurements are performed both on anchored and floating vessels. Acoustic field of vessels is changing along with their speed changing and is associatedwith acoustic activity of wave sources installed in vessel’s hull (main engines, electric generating sets, reduction gears, pumps, shaft-lines, piping, ventilating ducts etc) as well as hydro-dynamic sources such as screw propellers and water flow around the hull [5, 7]. Vibration energy generated by the onboard devicesis transferred through ship structural elements to water where it propagates in the form of hydro-acoustic waves of a wide frequency band
10

Influence of natural conditions on the imaging of the bottom of the Gdansk Bay by means of the side scan sonar

51%
Witos-Okrasinska D., Grelowska G., Kozaczka E.
Polish Maritime Research
|
2018
|
tom 25
|
nr Special Issue S1
The interest in underwater resources is the reason for the development of modern hydroacoustic systems, including side sonars, which find numerous applications such as: research of seabed morphology and sediment characteristics, preparation of sea sediment maps, and even in special cases of biocenoses such as sea grass meadows, detection of specific targets at the bottom such as shipwrecks, mines, identification of suitable sites for maritime infrastructure. Such applications require precise information about the position of the objects to be observed. Errors affecting the depiction of the bottom using hydroacoustic systems can be divided into errors associated with improper operation of measuring and support devices, systematic errors and random errors. Systematic errors result from the changing conditions prevailing in the analyzed environment affecting the measurement system. The errors affecting the correct operation of hydroacoustic systems can include: changing angle of inclination of the beam caused by the vessel’s movement on the wave or refraction connected to changes in the sound speed as the depth function
11

Processing data on sea bottom structure obtained by means of the parametric sounding

51%
Kozaczka E., Grelowska G., Kozaczka S., Szymczak W.
Polish Maritime Research
|
2012
|
tom 19
|
nr 4
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
12

The influence of Vistula water on the thermodynamic and acoustic parameters of the Gulf of Gdansk

51%
Kozaczka E., Grelowska G., Bittner P., Grelowski A.
Oceanologia
|
1995
|
tom 37
|
nr 2
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