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1
Content available Wykrywanie i lokalizowanie obiektów podwodnych sonarem bocznym jako element bezpieczeństwa żeglugi
Grządziel A., Nowak D., Wąż M.
Autobusy : technika, eksploatacja, systemy transportowe
|
2017
|
R. 18, nr 12
140--143, CD
PL
W artykule omówiony został aspekt wykrywania i lokalizowania obiektów podwodnych za pomocą hydrograficznego sonaru bocznego. Zwrócono uwagę na możliwość wykorzystania sonarów przeznaczonych do badań hydrograficznych w operacjach poszukiwania i detekcji obiektów minopodobnych. Dokonano ogólnej charakterystyki techniki sonarów bocznych zwracając szczególną uwagę na zalety i wady dwóch wariantów. W artykule zamieszczono wyniki wybranych prac sonarowych wykonanych z pokładu okrętu hydrograficznego ORP Arctowski.
EN
The article discusses the detection and localization of underwater objects with hydrographic side scan sonar. Attention was drawn to the possibility of using SSS technique in searching of mine-like objects MLO. Hull-mounted sonar and towed side scan sonar have been characterized, their advantages and disadvantages. The paper presents the results of selected sonar surveys performed on board the hydrographic ship ORP Arctowski.
2
Content available Wind shear detection based on direct measurements, remote sensing and numerical models
Chaładyniak D., Jasiński J., Pietrek S., Krawczyk K.
Zeszyty Naukowe Akademii Morskiej w Szczecinie
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2016
|
nr 48 (120)
75--80
EN
Wind has huge influence on take-off, landing and cruising of aircraft. Therefore measuring wind direction and speed as well as evaluating its structure are the most important tasks in meteorological support of flights. Wind shear, which is characterized by rapid changes of speed and/or direction, is one of the most hazardous phenomena for aviation. This phenomenon exists mostly in low tropospheric jet streams, areas of active atmospheric fronts, near convective clouds and strong temperature inversions. The paper proves that wind shear is mainly dependent on non-uniform layout of ascending and descending air currents and shows that this phenomenon can be detected by using ground sensors (ultrasonic anemometers), remote sensing methods (sodars, radars, wind profilers) and data from numerical mesoscale models.
3
Content available Method for improving multibeam sonar bearing accuracy
Leśniak W., Marszal J., Salamon R., Zachariasz K., Schmidt J.
Hydroacoustics
|
2009
|
Vol. 12
98-108
EN
The paper presents a simple method for improving multibeam sonar bearing accuracy. The principle proposed here is similar to the monopulse method, a solution commonly used in radars and sonars. With no manual or automatic beam rotation, the method offers a substantial reduction in the demand for sonar computational effort. It significantly reduces bearing error for a relatively high signal to noise ratio. The paper gives a boundary value of the output signal to noise ratio which when exceeded satisfactorily improves bearing accuracy.
4
Content available Using multibeam echoes in seafloor characterisation and classification
Łubniewski Z.
Hydroacoustics
|
2008
|
Vol. 11
265-270
EN
The method of seabed identification and classification from multibeam sonar echoes is presented. The proposed approach is based on calculation of a set of parameters of an echo envelope, similarly as in seafloor classification using single beam echosounder. These parameters are extracted for each consecutive beam allowing the estimation of their dependence on the seafloor incident angle. The relation between seabed type and calculated echo parameters and its angular dependence, is investigated. The results obtained using sonar data records from several bottom types in Gdańsk Bay water region are presented and discussed. It has been primarily justified that the proposed approach may be useful in seafloor characterisation.
5
Content available SHL-101/T SONAR - results of the harbour and sea trials
Kotłowski A., Męciński W., Okuniewski M, Prosińska E., Zając R.
Hydroacoustics
|
2008
|
Vol. 11
139-148
EN
The safeguard of seaways, naval basis, harbours and sea frontiers from minefields, attackers, gun-running is essential in hazardous nowadays. Particularly modern sea mines sometimes buried and make in stealth technology are very difficult to detect. Therefore the echo-ranging detection systems require state-of-the-art hardware and efficient processing algorithms to protect sea areas. Such up-to-date hydroacoustic equipment was developed by R&D Marine Technology Centre. The SHL-101/T system is the triple frequency, wideband and very high resolution hull-mounted minehunting sonar. It was put into service to Polish Navy minesweeper on April 2007. Sonar underwent factory, harbour and sea acceptance trials. Presently Polish Navy carries out further exploitation and military tests. The results are remarkable and they enable to explore mysteries of the sunken objects in the Gdansk Gulf. The paper presents the results of SHL-101/T sonar harbour and sea trials. Its performances for different detection and classification modes are also depicted. Additionally displays of the found various underwater objects are included and detailed discussed.
6
Content available Laboratory model of high frequency sonar
Buszman K., Szymczak W.
Hydroacoustics
|
2008
|
Vol. 11
39-46
EN
This article contains the construction and laboratory application of high frequency sonar model. In view of working in laboratory conditions, they must be fulfilled succeeding parametric cases: very narrow beam, low level of side lobes and low acoustic power of transmitted impulse sounding. When all of these conditions are fulfilled, it makes possible the explanation to students some terms like depth, angular resolution and making clear, that water is the best environment to acoustic waves transmission. Furthermore, there is used automatic component, namely rotary antenna, which make possibility to precision area scanning.
7
Content available Experimental evidence for enhanced target detection by sonar in bubbly water
Leighton T., Finfer D., White P.
Hydroacoustics
|
2008
|
Vol. 11
181-203
EN
A sonar system has been developed which allows one to discriminate targets from scattered energy from bubbles. The underlying theory and experimental testing of this system are presented. The effectiveness of this sonar system is demonstrated through experimentation within a large fresh water tank in which bubble clouds are generated. Some of the practical requirements associated with such an experiment are detailed.
8
Content available remote Localisation of underwater objects using side scan sonars
Makar A.
Reports on Geodesy
|
2003
|
z. 1/64
265-271
EN
Detection of the underwater obstacles is the essential issue for ensuring the navigation safety of the ships and the submarines, during dredging, putting underwater pipes. For bottom searching are used, among other things, side scan sonars (SSS). Detected objects are shown on echograms in graphic form. Interpretation of echograms, location and determination of geometrical dimensions of detected objects are the compound of many parameters. In this paper the metbod of location of underwater objects using side scan sonars has been shown.
9
Content available remote Comparative positioning of ships on the basis of neural processing of digital images
Stateczny A.
Reports on Geodesy
|
2003
|
z. 1/64
295-301
EN
Satellite and radar systems have been the main information sources in marine navigation in recent years. Apart from commonly known anti-collision functions, the marine navigational radar constitutes the basis for a future comparative system of ship positioning. The sonar is an additional source of image information in the system. In this way, the data are derived from observing the surroundings of the ship's total measuring area. The system of comparative navigation is an attractive alternative to satellite navigation due to its autonomy and independence from external appliances. The methods of analytic comparison of digitally recorded images applied so far are based on complex and time-consuming calculation algorithms. A new approach in comparative navigation is the application of artificial neural networks for plotting the ship's position. In the positioning process, previously registered images can be made use of, as wen as their positions plotted for instance by means of the GPS system or by geodetic metbods. The teaching sequence is constituted by the registered images correlated with positions; it is performed earlier and can last for any length of time. After the process of teaching the network is completed, the dynamically registered images are put on the network input as they come, and a position interpolation is performed based on images recognized as closest to the image analyzed. A merit of this method is teaching the network with real images, along with their disturbances and distortions. The teaching sequence includes images analogous to those that will be used in practice. During the system' s working the response of the network (plotting the ship's position) is almost immediate. A basic problem of this method is the need for previous registration of numerous real images in various hydrometeorological conditions. The registered images should be subjected to digital processing, to the compression process in particular. One of the processing methods is encoding the image by means of projection method, and next giving the encoded vector to the input of GRNN (General Regression Neural Networks). The article presents a method of processing the image through encoding by projection method and interpolating the ship's position by GRNN network.
10
Content available remote Analiza metod geometrycznych interpretacji pomiarów wykonanych sonarem w aspekcie rozpoznania obiektów leżących na dnie
Felski A., Hac B.
Zeszyty Naukowe Akademii Marynarki Wojennej
|
1998
|
R. 39 nr 1 (136)
5-18
PL
W artykule rozważane są możliwości określania podstawowych cech geometrycznych obiektów leżących na dnie morza w oparciu o pomiary wykonane sonarem bocznym.
EN
In this paper we consider possibilites to identifying basic geometric features of objects situated on the seabed by means of a side scan sonar.
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