Wyniki wyszukiwania dla: SHALLOW WATER ACOUSTICS

• Hydrodynamic Pressure Field of a Ship on Shallow Water

  Publikacja

  • J. Bielański

  - Rok 2013

  Results of calculations of the hydrodynamic pressure field around the ship were obtained by application of the boundary element method. Hydrodynamic field was calculated for a Polish Navy’s tugboat and transport ship using a program called SHiPP and compared with measurements of the field taken on river near Swinoujscie for two identical tugs H-4 and H-10. Next, a series of HPF calculations was carried out on planes situated at...

• Shallow Water Experiment of OFDM Underwater Acoustic Communications

  Publikacja

  • I. Kochańska
  • J. Schmidt
  • J. Marszal

  - Archives of Acoustics - Rok 2020

  The large variability of communication properties of underwater acoustic channels, and especially the strongly varying instantaneous conditions in shallow waters, is a challenge for the designers of underwater acoustic communication (UAC) systems. The use of phase modulated signals does not allow reliable data transmission through such a tough communication channel. However, orthogonal frequency-division multiplexing (OFDM), being...

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• Theoretical Model of Acoustic Wave Propagation in Shallow Water

  Publikacja

  • E. Kozaczka
  • G. Grelowska

  - Polish Maritime Research - Rok 2017

  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”...

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• Balance errors in numerical solutions of shallow water equations

  Publikacja

  • D. Gąsiorowski

  - TASK Quarterly - Rok 2007

  The analysis of the conservative properties of the shallow water equations is presented in the paper. The work focuses on the consistency of numerical solution of these equations with the conservation laws of mass and momentum. The investigations involve two different conservative forms which are solved by an implicit box scheme. The theoretical analysis supported by numerical experiments is carried out for rectangular channel...

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• Assessment of ship squat in shallow water using CFD

  Publikacja

  • J. Jachowski

  - Rok 2007

  Referat zawiera wstęp do problemu modelowania efektów wody ograniczonej przy użyciu komercyjnego programu Fluent opartego na metodzie elementów skończonych.

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• Assessment of ship squat in shallow water using CFD

  Publikacja

  • J. Jachowski

  - Archives of Civil and Mechanical Engineering - Rok 2008

  Artykuł zawiera wstęp do problemu modelowania efektów wody ograniczonej przy użyciu komercyjnego programu Fluent opartego na metodzie elementów skończonych.

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• Testing OFDM Transmission Schemes for Shallow Water Acoustic Communications

  Publikacja

  • I. Kochańska
  • H. Lasota

  - Rok 2013

  Large variability of communication properties of underwater acoustic channels, and especially strongly varying instantaneous conditions in shallow waters, is a tough challenge for the designers of underwater acoustics communication (UAC system. There is a need for developing adaptive signaling schemes that would dynamically optimize signal parameters in both physical and link layers of communication protocols. The orthogonal frequency...

• Shallow-Water Acoustic Communications in Strong Multipath Propagation Conditions

  Publikacja

  • I. Kochańska
  • A. Schmidt
  • J. Schmidt

  - Rok 2024

  A phenomenon that has a strong impact on signal transmission conditions in Underwater Acoustic Communication (UAC) systems is multipath propagation. As a result of multipath propagation, the transmitted signal undergoes time dispersion which results in inter-symbol interference observed on the receiving side. Time dispersion is large, especially in horizontal channels in shallow waters which significantly limits the transmission...

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• Shipping Low Frequency Noise and Its Propagation in Shallow Water

  Publikacja

  • E. Kozaczka
  • G. Grelowska

  - ACTA PHYSICA POLONICA A - Rok 2011

  One of the most significant factor influencing acoustical climate of the sea is underwater noise generated by moving ships. If the considered sea area has features of the shallow water, namely the wave frequency fulfils relation f < 10c/h, where c denotes phase speed of sound, and h is depths of the sea, then in certain distance from the wave source specific image of sound pressure distribution in the mean of wave modes appears....

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• Analysis of hydrodynamic pressure fields of motorboats and pontoons in shallow water

  Publikacja

  • J. Bielański

  - HYDROACOUSTICS - Rok 2016

  The article presents the results of calculations of the pressure fields generated by a motorboat at the bottom of a shallow sea. Calculations were made using the boundary elements method (BEM), arranged on the surface of the boat and the bottom of the sea. This method is described in [3], and applied on a free surface linearized boundary condition. Results for four different lengths of motorboats, from 2.85 m to 9.5 m, sea depth...

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