Wyniki wyszukiwania - BazTech

1

Signals parametrization method of sailing vessels

Buszman K., Gloza I.

Hydroacoustics

|

2016

|

Vol. 19

27--36

EN

The expansion of maritime transport is directly connected with increased risk of the appearance of unidentified vessels in the approaches to ports, wind farms, and other sensitive places in the water-body. Creating a parameters database of sailing objects, based on recorded dynamic variations of different physical fields with the specified aims of increasing security within the strategic offshore areas.

2

Uncertainty analysis of the determination noise source direction using the tetrahedron hydrophone array

Gloza I., Józwiak R., Pawlik P., Bartko W.

Hydroacoustics

|

2015

|

Vol. 18

59-68

EN

The analysis of the uncertainty of the determination of the noise source direction in the aquatic environment is presented in this paper. The type A uncertainty of the bearing algorithm was determined on the bases of multiple measurements of the hydroacoustic pressure by means of the TC4032 type hydrophones and the GPS device data. The influence of the non-linearity of the amplitude-frequency characteristic on the uncertainty of the determination of the noise source direction, was also described. The influence of water density, electromagnetic disturbances and irregular noises on the final uncertainty was determined. On the bases of the determined uncertainty components the uncertainty budget, of the determination of the angle showing the direction from which hydroacoustic waves are coming, was prepared.

3

The one – third – octave spectrum as a method of vessel identification

Gloza I., Józwiak R., Buszman K.

Hydroacoustics

|

2014

|

Vol. 17

63--68

EN

The subject of the examinations carried out is hydroacoustic noise in coastal zones. Under these conditions natural noise and the noise from moving vessels affect each other, as well as interference from industrial infrastructure located close to the coast. Both natural noise and noise caused by human activity affect the detection and identification of noise sources in these conditions. Experiments have been performed by the mobile measuring module in the Gulf of Gdansk. This showed that it can extract spectrum components, based on the results of underwater noise. These components allow the detection of moving objects. The collected database of measurements enabled the comparison of one-third-octave spectra of three different ships. The components specific to the type of vessel could extracted as a result of comparison. Consequently one of the three tested vessels could be identified.

4

Sound intensity distribution as an underwater acoustic investigation process

Gloza I., Buszman K.

Hydroacoustics

|

2014

|

Vol. 17

57--62

EN

The subject matter of this research is underwater noise generated by sailing vessels in shallow seas. The classical method for measurement of underwater noise involves measuring effective acoustic pressure and fits for purposes in the free far field of the source. Despite its popularity, the method does have some significant limitations. Investigations of underwater noise generated by moving vessels in shallow seas are almost solely confined to the near field. In addition, this has a high level of interference and numerous wave reflections. This is why, as well as using the acoustic pressure measurement method, a complementary method for measuring acoustic wave intensity is used increasingly often. The measurements were taken using an underwater measurement module equipped with a set of detectors. Submerged at 20m, the object moved along a designated trajectory at a preset speed (as determined by the parameters of the ship’s machinery). Because all of the on-board equipment generates ship-specific noise, additional measurements were taken of the vibrations generated by selected ship’s machines to identify those sources. If known, the distribution of the acoustic field from vessels helps to identify the characteristic frequencies generated by the ship’s equipment and machinery. The paper includes a comparison of acoustic wave intensity and acoustic pressure measurements taken under the same ambient conditions and over the same period.

5

Ranges and equipment for the measurement of the ship's underwater signatures

Gloza I., Malinowski S. J., Marchalewski B.

Hydroacoustics

|

2012

|

Vol. 15

39-48

EN

Controlling unwanted signatures on warships is a most important effort for ship designers and naval operators. A great attempt is considerate in this field in many countries such as the USA, Germany, Sweden, Norway and in Poland as well. This paper presents ranges and techniques for the investigation of the underwater physical fields radiated by different surface ships and submarines. The Polish Naval Academy and the Naval Test and Evaluation Ranges (NTER) check and next decrease generated by the ship’s physical fields. These underwater signals can be hydroacoustic, hydrodynamic, electric, magnetic and seismic in nature. In order to have good quality measurements, there are land and sea installations, platforms on trucks, and what more a special laboratory aboard the ship. The Ranges also have a fixed and transportable multi–sensor equipment installed in a single module. This apparatus is now being used both for the measurement and for the gathering of scientific data which are next further research and analysis.

6

The old and new procedures for the investigation of underwater signatures

Gloza I., Malinowski S. J., Marchalewski B., Dobrzeniecki J.

Hydroacoustics

|

2011

|

Vol. 14

55-60

EN

This paper presents the results of old and new techniques for the investigations of underwater acoustic fields radiated by different objects. In the Navy Test and Evaluation Ranges (NTER), we monitor the ship radiated underwater noise, pressure and other signatures. They are of major importance to sea mines, surface ships and submarines. The NTERs contain an accurate measurement system consisting of a bottom-mounted hydrophone array, which is used for different running vessels. We also have a special laboratory ship and a transportable multisensor module, which is the most recent Polish Naval Academy product. Nowadays, the problem of protecting the civilian and military harbor facilities is becoming more and more important. There is always a threat to the ports from submarines and terrorists who dive under the water.

7

The multi-influence passive module for underwater environment monitoring

Gloza I., Buszman K.

Hydroacoustics

|

2011

|

Vol. 14

47-54

EN

The threats to the operation of a ship close to the coast and harbor can be significantly different to those of deep-water operation. It is obvious that any operation in this environment requires a good understanding of how the ship’s signatures behave. Quite a few different systems exist which can detect and track underwater moving targets. The most practical systems use underwater passive detectors. Therefore we often install in such environment multi-sensor measuring device to verify the whole situation. Designed by the Polish Naval Academy mobile multi-sensor module serves such purpose. This module consists of acoustic, magnetic, electric, seismic and pressure sensors fitted to the nonmagnetic tripod. This makes possible to measure signatures to high degree of accuracy in a variety of environments in real time.

8

Investigation of the underwater noise produced by ships by means of intensity method

Kozaczka E., Domagalski J., Gloza I.

Polish Maritime Research

|

2010

|

nr 3

26-36

EN

This paper presents results of research on spectral structure of underwater noise acoustic field radiated into water by selected ships moving in shallow waters. Underwater acoustic field of ships in motion is associated with acoustic activity of ship mechanisms and equipment under work. Vibration energy radiated by the mechanisms and devices is transmitted by ship structural elements to surrounding water where it is propagated in the form of acoustic waves of a wide frequency band. In this paper are presented results of the research on propagation of energy of acoustic waves in the near fiel, obtained from acoustic pressure measurements by means of two sensors located close to each other.

9

Ship's underwater noise measurements using sound intensity method

Gloza I.

Hydroacoustics

|

2009

|

Vol. 12

53-60

EN

Ship noise is a most important part of the field of underwater acoustics. Its reduction and monitoring is an 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 systems. Sound intensity is the vector quantity which informs us about the sound power flux, the position and 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 was examined. The two measuring hydrophone instrumentation systems were earlier calibrated. Our results have been obtained using digital methods, where was used PULSE measuring system.

10

Vibration and radiated noise of a small ship

Gloza I.

Hydroacoustics

|

2008

|

Vol. 11

87-96

EN

Extensive measurements "in situ" both of the sound intensity and the vibration were made of M25, a small ship (length 8 m , beam 4 m, displacement 2 tons) powered by 20 kW a direct-drive low-speed diesel engine. A small ship creates a series of harmonics which amplitudes and frequencies are connected with ship speed. The underwater sound measurement was performed for anchored condition. In this paper, two different methods of measurement were used, which provide complementary information. A static method to measure noise from an anchored ship was used when only the main engine was running. In addition to the radiated noise measurements, vibration measurements were conducted aboard this ship. The coherence function was performed to associate each component of underwater noise with the vibrating part of the engine which generates it. The calculation of the sound intensity was made to locate the main source of noise on board. Underwater noise from small ships elevates the natural ambient by 10 - 20 dB in many area; the effects of this noise on the biological environment have been rarely reported.

11

Artificial neural networks for interpolation and identification of underwater object features

Balicki J., Gloza I.

Hydroacoustics

|

2008

|

Vol. 11

1-10

EN

Artificial neural networks can be applied for interpolation of function with multiple variables. Because of concurrent processing of data by neurons, that approach can be seen as hopeful alternative for numerical algorithms. From these reasons, the analysis of capabilities for some models of neural networks has been carried out in the purpose for identification of the underwater object properties. Features of the underwater objects can be recognized by characteristics of a amplitude according to the frequency of measured signals. The feed-forward multi-layer networks with different transfer functions have been applied. Those network models have been trained by some versions of back-propagation algorithm as well as the Levenberg-Marquardt gradient optimization technique. Finally, for determination of the amplitude for the frequency of signal by the two-layer network with the hidden layer of the radial neurons has been proposed.

12

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

Kozaczka E., Domagalski J., Grelowska G., Gloza I.

Polish Maritime Research

|

2007

|

nr 4

40-46

EN

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 associated with 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 devices is transferred through ship structural elements to water where it propagates in the form of hydro-acoustic waves of a wide frequency band.

13

Application of PCA as an acoustical signal processing tool for object classification purposes

Soszyński P., Gloza I.

Hydroacoustics

|

2005

|

Vol. 8

193-198

EN

The authors presented a technique for an optimal representation of acoustical signals for further object classification purposes using different statistical and neural methods. It is based on principal component analysis (PCA) which is a transformation of vectors localized in k-dimensional observation (feature) space into lower n-dimensional component space retaining majority of included information. The resulting improvement in classification efficiency by a chosen statistical classifier was verified by a numerical experiment.

14

Sound Emitted by Ships and Grey Seals into Water Environment

Gloza I.

Mechanika / Akademia Górniczo-Hutnicza im. St. Staszica

|

2004

|

T. 23, z. 2

161-168

EN

In this paper we give a brief introduction to the marine behaviour of the grey seals and describe the current state of knowledge about their hearing and influence of ship noise into their life. The Naval University had the opportunity to record these sea mammals vocalizations in the Polish peninsula Hel. The waters of the Baltic Sea are major area for shipping, military exercises and activities including: merchant vessels movement, surface warships and submarines exercises, torpedo testing and firing ranges, therefore they are full of noise. Ship noise spectra are usually in two categories: broad-band noise, which has a continuous spectrum; and tonal noise, which contains discrete frequencies or lines. Additionally the acoustic radiation is also characterized by passing and irregular noise caused by impacts, loose equipment and machinery changes of state. Propeller cavitation is also a major problem here.

PL

Dźwięki emitowane przez obiekty podwodne są źródłem fal akustycznych rozchodzących się w środowisku wodnym. Proces ten może mieć szkodliwy wpływ na równowagę ekologiczną, zwłaszcza w przypadku takich źródeł jak statki i okręty, w akwenach o dużym nasileniu ruchu. Głównym celem artykułu jest przedstawienie wyników obszernych badań doświadczalnych związanych z transmisją do wody energii akustycznej przez jednostki pływające. W pracy przedstawiono metodykę oceny transmisji do wody energii drgań mechanizmów okrętowych znajdujących się wewnątrz kadłuba. Przedstawiono również wyniki badań dźwięków emitowanych przez fokę szarą w postaci wąskopasmowych widm mocy. Mając na uwadze, że rozkład drgań na powierzchni kadłuba, a także warunki propagacji fal akustycznych w morzu płytkim są procesami nieliniowymi, zależnymi od wielu czynników, wnioski oparto głównie na wieloletnich badaniach prowadzonych w warunkach naturalnych.

15

Underwater ship passport

Gloza I.

Hydroacoustics

|

2004

|

Vol. 7

47-54

EN

For years in the Polish Navy extensive measurements have been made of the underwater-radiated noise by different kinds of surface ships. To identify the source of noise, the level of vibration was also measured by accelerometers inside each ship section. Radiation at discrete frequencies caused by low frequency hull vibrations, excited by the machinery is easily detected and must be reduced as much as possible. The radiated noise spectra show high-level tonal frequencies from propellers and main engines. They varied with speed of the vessel in a complex manner. Ship 's service diesel generator (SSDG) creates a series of harmonies which amplitudes and frequencies are independent of ship speed. The articles documents series characteristics of the surface ship's radiated underwater noise data. The noise from small vessels elevates the natural ambient noise by 10-40 dB. Third-octave bandwidth analyses are too wide separation of the individual radiated components of ship noise that 's why accurate narrow-band spectra (sometimes less than 0,1 Hz) have been made.

16

Investigation of propagation of acoustic wave generated by a moving ship

Gloza I., Domagalski J.

Hydroacoustics

|

2003

|

Vol. 6

183--188

EN

A moving ship is a source of acoustic perturbations resulting from her complex hull being a surface of irregular shape and from a rotational source - the propellers. The sources generate acoustic waves in wide frequency band. In case of a shallow sea the prapagation of the acoustic waves for varying source-detector distances and different frequencies are described applying the modes and ray theory.

17

Identification of the ships underwater noise sources in the coastal region

Gloza I., Malinowski S. J.

Hydroacoustics

|

2002

|

Vol. 5

9--16

EN

The results of the investigations of underwater noise radiated by ships at the background of the ambient sea noise in the coastal region are presented. Sounds in shallow water are inherently modified by the local environment. Based on the results of the measurements of both the ambient noise and the noise radiated by ships the investigations of the influence of the ship's motion on the ambient sea noise were carried out. What more the noise field at the sea in the coastal region is notably influenced with the technical noise, especially connected with the human's activity.

18

Struktura pola akustycznego szumów podwodnych jednostki pływającej w polu bliskim

Gloza I., Dobrzeniecki J., Domagalski J.

Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje

|

2001

|

Vol. 83, nr 27

269-274

EN

Investigations of acoustical field structure of the underwater ship noise in the near field are presented in the paper. These investigations were done for the purpose ship classification.

19

Identyfikacja źródeł zaburzeń podwodnych okrętu z wykorzystaniem funkcji koherencji

Baranowska A., Gloza I.

Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje

|

2001

|

Vol. 83, nr 27

245-250

PL

W pracy przedstawiono metodę identyfikacji źródeł zaburzeń podwodnych okrętu. Badano wpływ pracy silników głównych oraz zespołu prądotwórczego na całkowity szum podwodny okrętu. Zaproponowana metoda koherencyjna pozwala z jednej strony na identyfikację źródeł zaburzeń, z drugiej zaś na określenie ich udziału w szumie okrętu. Znajomość źródeł szumu podwodnego okrętu może być pomocna między innymi przy opracowaniu metod ich tłumienia a tym samym minimalizacji szumu podwodnego okrętu. Wyniki przeprowadzonych badań znajdą zastosowanie w dalszych pracach dotyczących wpływu parametrów pracy urządzeń okrętowych na zaburzenia podwodne okrętu. Przedstawione w niniejszej pracy wyniki dotyczą badań zaburzeń hydroakustycznych pochodzących od okrętu na uwięzi. W przyszłości będą również przeprowadzenie badania dotyczące źródeł zaburzeń poruszającego się okrętu.

EN

The identification problem of the ship disturbance sources was studied in the paper. The paper presents the method of measurements and investigations. The investigations were carried out on the basis of the results of underwater ship noise and vibration measurements. Underwater ship noise was measured by hydrophone. To find the sources of noise, the level of vibration was measured by accelerometer. The analysis of underwater ship noise shows that the ship's diesel engine and auxiliary machinery are very important components of ship disturbance. Therefore the influence of these ship noise sources were considered. The coherence method was used to identify the ship disturbance sources.

20

Underwater noise radiated by ships, their propulsion and auxiliary machinery, and propellers

Malinowski S. J., Gloza I., Domagalski J.

Hydroacoustics

|

2001

|

Vol. 4

165--168

EN

These underwater radiated noise and vibration measurements were conducted on a full-scale ship in August 2000. During the trails it was found that several spike noises are dominant. To find the location of high vibration level places and its frequencies, and the machines, which generated high level point noise components, 4 accelerometers were fixed in the engine and auxiliary rooms .We were using this system to find the relationship between certain manoeuvres and the vibration level caused by them. Propellers and engines are usually the major sources of noise in ships but gearboxes can also be significant contributors. The way of mounting of the machines and the resulting vibration of the hull are determining issues in the radiation of underwater noise. Naval Test and Evaluation Acoustic Ranges contain an accurate radiated noise measurement system consisting of a bottom-mounted hydrophone array for sailing condition and a stationary range. The sophisticated digital narrow-band instruments and analogue recorders were used by us.