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Catalog Publications

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Year 2013
  • Detection of Objects Buried in the Sea Bottom with the Use of Parametric Echosounder
    Publication

    - Archives of Acoustics - Year 2013

    The paper contains results of a in situ research main task of which was to detect objects buried, partially or completely, in the sea bottom. Object detecting technologies employing acoustic wave sources based on nonlinear interaction of elastic waves require application of parametric sound sources. Detection of objects buried in the sea bottom with the use of classic hydroacoustic devices such as the sidescan sonar or multibeam...

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  • Diver Observations by Means of Acoustic Methods
    Publication

    Searching for objects, especially small ones, moving under water near its the free surface, is always not an easy task. Designing tools for the detection of such targets is a real challenge when the possibility of a terrorist attack is a real threat. This paper presents some aspects of diver detection by means of acoustics methods, both active (side scan sonar) and passive ones (linear receiving antenna). This approach is quite...

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  • Effect of initial imperfection on buckling of thin-walled I columns

    Effects of initial geometrical imperfections on critical buckling loads of thin-walled I columns are investigated. Torsional and flexural buckling are taken into account. The column behaviour is described in accord to the theory of thin-walled beams with nondeformable cross-section. Some numerical examples and conclusions related to effects of imperfections on properties of the critical loads are presented.

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  • Elastic distortional buckling of thin-walled bars of closed quadratic cross-section

    In this study a tin-walled bar with closed quadratic cross-section is considered. The elastic stability of axially compressed bar related to the cross-section distortion is investigated. The governing differential equatio is derived with aid of the principle of stationary potential energy. The critical load for simply supported bar is found in an analytical form and it is copared with the FEM solution. Sufficient accuracy of the...

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  • Experiment with small objects floating under water in the harbor security aspect.
    Publication

    - Year 2013

    Observation of the underwater area is the element of general trend which primary purpose is to protect and enhance the safety of the selected region. The aim of the paper is to present the acoustic characteristics of typical objects floating on the surface or under the water, which constitute some knowledge on how to detect these objects. Create a catalog of acoustic signatures and acoustic images of objects mostly floating under...

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  • Gdansk Bay sea bed sounding and classification of its results
    Publication

    The main goal of this paper is to describe the results of sounding the Gdansk Bay sea bed by using a SES-2000 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...

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  • GeoSPAR Project. Validation and selection methods of geoinformation analysis using GIS for ranking and forecasting of terrorist threats and criminal events
    Publication

    - HYDROACOUSTICS - Year 2013

    The paper presents the description of work activities which have already been done within the first two stages – WorkPackage 1 and WorkPackage 2 - of the GeoSPAR Project. In such a context the general conceptual design of the GIS system and associate web service was presented and analysed. In addition, the operational and technical requirements for the GeoSPAR system have been specified and discussed; with special emphasis on system...

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  • HYDROACOUSTIC NOISE MEASUREMENTS
    Publication

    - Year 2013

    The paper deals mainly with investigation of underwater noise that propagation is in shallow water. In this paper has been presented the experimental investigation results concerning the distribution of the sound field pressure generated by moving ships in the shallow water at the small distance from the ship. The main acoustical characteristics describing features of the field are spectrograms in pseudo 3D system – distance and frequency...