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    Wyświetlanie 1-11 z 11
    Tytuł:
    Data compression and clustering of one-third-octave spectra by acoustical colors
    Autorzy:
    Józwiak, R.
    Nissen, I.
    Listewnik, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/332570.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    cumulative value
    acoustical colors
    hydroacoustic measurement
    underwater communication
    Opis:
    This article presents a new approach for the data compression and clustering of one-third octave spectrum by using "acoustical colours". Using in-situ measurements by the IGLOO – sensor nodes it can show that this approach allows a clustering of the colors for a quick look classification. This is helpful using wireless acoustical transmissions with restricted transfer volume in underwater sensor networks without jamming their own measurements.
    Źródło:
    Hydroacoustics; 2017, 20; 85-92
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of sound extinction and echo interference in densely aggregated zooplankton
    Autorzy:
    Gorska, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/48619.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    fish
    zooplankton
    aggregation
    hydroacoustic measurement
    extinction
    echo interference
    krill
    evaluation
    Opis:
    The investigation of sound extinction and echo interference is important as regards the accurate assessment of the abundance of densely aggregated zooplankton. To study these effects, the analytical model describing sound backscattering by an aggregation of isotropic scatterers (Rytov et al. 1978, Sun & Gimenez 1992) has been extended to the case of densely aggregated elongated zooplankton. The evaluation of the effects in the case of a dense krill aggregation demonstrates that they can be significant and should be taken into account.
    Źródło:
    Oceanologia; 2000, 42, 3
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Observations on relations between marine aerosol fluxes and surface-generated noise in the Southern Baltic Sea
    Autorzy:
    Markuszewski, P.
    Klusek, Z.
    Nilsson, E.D.
    Petelski, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2079072.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    marine aerosol
    aerosol flux
    noise measurement
    underwater noise
    sea spray
    hydroacoustic measurement
    meteorological condition
    Baltic Sea
    Opis:
    This study presents the preliminary results of combining underwater acoustic ambient noise measurements with those of in-situ sea spray fluxes (SSF). Hydroacoustic measurements (in the frequency range 80 Hz –12.5 kHz) were made using an underwater noise recording system developed at the Institute of Oceanology of the Polish Academy of Sciences which was then deployed in the southern Baltic Sea. The simultaneous measurements of coarse sea spray fluxes (with particle diameters ranging from 0.5 to 47 µm) were made on board the r/v Oceania using the gradient method. Observations were conducted for the duration of the passage of an atmospheric front that lasted 2.5 days (60 hours of measurements). There were significant differences in the sound pressure level (SPL) and aerosol fluxes observed between the first part of measurements (developing wave state) and the second part (developed waves). Wave parameters, such as peak period, significant wave height, wave age, and mean wave slope acquired from the WAM (WAve Model), were used to investigate the impact of wave field properties on noise and aerosol flux measurements. We observed different behaviours in the power spectrum density (PSD) levels of noise for these parameters depending on the wave state development.
    Źródło:
    Oceanologia; 2020, 62, 4PA; 413-427
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysing the impact on underwater noise of changes to the parameters of a ship’s machinery
    Autorzy:
    Buszman, Krystian
    Powiązania:
    https://bibliotekanauki.pl/articles/1573917.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    shipping noise
    hydroacoustic passive measurement
    narrowband
    1/3-octave analysis
    diagnosis
    classification
    Opis:
    A ship moving over the surface of water generates disturbances that are perceived as noise, both in the air and under water. Due to its density, water is an excellent medium for transmitting acoustic waves over long distances. This article describes the impact of the settings of a ship’s machinery on the nature of the generated noise. Our analysis includes the frequency characteristics of the noise generated by the moving ship. Data were obtained using an underwater measurement system, and the measured objects were two ships moving on specific trajectories with certain machinery settings. The acquired data were analysed in the frequency domain to explore the possibilities of the acoustic classification of ships and diagnostics of source mechanisms.
    Źródło:
    Polish Maritime Research; 2020, 3; 176-181
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of maximum-length sequences to impulse response measurement of hydroacoustic communications systems
    Autorzy:
    Mazurek, R.
    Lasota, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/332528.pdf
    Data publikacji:
    2007
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    There is a growing interest in digital transmission of telemetry data on ultrasonic waves. The dependence of signal attenuation on squared frequency, specific to the hy-droacoustic systems, induces problems that do not exist in monochromatic, narrowband radio communications systems. For adapting the transmission parameters to current propagation conditions, a precise knowledge of instantaneous changes of channel performances is needed. Simulating and testing of broadband communications techniques require robust, reliable and efficient method of impulse response measurements in natural exploitation conditions. The paper presents the MLS (Maximum-Length Sequence) correlation method applied to impulse response measurements of electroacoustic transducers as elements of communication chain.
    Źródło:
    Hydroacoustics; 2007, 10; 123-130
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ocean average current measurement using acoustic phase monitoring
    Autorzy:
    Zieliński, A.
    Zhou, L.
    Butowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/331688.pdf
    Data publikacji:
    2008
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    ocean-related activities
    acoustic phase monitoring
    hydroacoustic
    Opis:
    Knowledge of water currents is important in several ocean-related activities. Typically, current speed and direction are measured at a certain fixed location and depth (or depth profile) by a suitable current meter. In this paper, we propose a novel method for average current speed measurement along a path, based on acoustic phase monitoring. In this method, a transmitter and a receiver are installed at the ends of a designated path. A transmitted sinusoidal signal propagates along the path to the receiver. Intervening currents will introduce Doppler frequency shifts that can be measured as a rate of phase change in the received signal. The phase is recovered by means of a phase detector and unwrapping techniques. The desirable feature of the proposed method is that average current speed is monitored along the entire path. Moreover, the estimated frequency shift via the phase measurement achieves a higher accuracy in current measurement than does a measure of frequency directly by an FM demodulator.
    Źródło:
    Hydroacoustics; 2008, 11; 459-467
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stanowisko do wyznaczania odpowiedzi impulsowej kanału hydroakustycznego
    Measurement stand for estimate of hydroacoustic channel impulse response
    Autorzy:
    Kaczorek, P.
    Studański, R.
    Żak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/267360.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
    Tematy:
    odpowiedź kanału na pobudzenie sygnałem modulowanym ciągiem pseudoprzypadkowym
    kanał hydroakustyczny
    channel response to signal modulated by Pseudo Random Binary Sequence
    hydroacoustic channel
    Opis:
    W artykule opisano metodę oraz stanowisko badawcze, za pomocą, którego obliczono odpowiedzi kanału hydroakustycznego na pobudzenie sygnałem modulowanym ciągiem pseudoprzypadkowym PRBS (ang. Pseudo Random Binary Sequence). Omówiono wyniki badań w warunkach laboratoryjnych oraz w jeziorze i basenie portu morskiego. Badania wykonano w warunkach statycznych.
    The method and measurement stand for estimate of hydroacoustic channel response to signal modulated by Pseudo Random Binary Sequence (PRBS) stimulation are described in the paper. Results of research in laboratory conditions and real environment like lake and harbor are presented. The measurements were made in static conditions.
    Źródło:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2017, 57; 33-36
    1425-5766
    2353-1290
    Pojawia się w:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hardware implementation of parametric algorithm for asynchronously gathered measurement data based on the FPGA technology
    Autorzy:
    Janowski, T.
    Szworski, K.
    Zając, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/332532.pdf
    Data publikacji:
    2009
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    hardware implementation
    FPGA technology
    hydroacoustic system
    Opis:
    The hydroacoustic system based on DOA estimation utilizes passive antenna composed of many hydrophones. The samples of the arriving acoustic signal must be gathered synchronously from each hydrophone. This enables to take advantage of parametric processing signals methods. These methods make possible determination of the amplitude and the phase relationship among particular hydrophones. The newest complex systems made up of many sub modules uses network solutions. In the case of Ethernet network some standards (e.g. Precision Time Protocol) are defined to enable synchronization of the data (samples) gathered from many hydrophones by the clock synchronization. When the antenna consists of few hydrophones then the special concentrator connected point-to-point to hydrophones can be utilized. This article discusses the issue related to PTP as well as concentrator based on FPGA technology, which uses simple UDP protocol. In the case of concentrator the synchronous method of the I/Q detection which not requires synchronous samples acquisition is also presented.
    Źródło:
    Hydroacoustics; 2009, 12; 83-90
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A measurement of 3-D water velocity components during ROV tether simulations in a test tank using hydroacoustic doppler velocimeter
    Autorzy:
    Kwapisz, L.
    Narewski, M.
    Rowiński, L. A.
    Żrodowski, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/332105.pdf
    Data publikacji:
    1997
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    A computer simulation of ROV tethers performance could be done more precisely if velocity field of water flowing around the tether cable is known. The paper describes operation and performance of the doppler acoustic velocimeter ADVlab. A brief outline of the procedures and related problems with determination of 3-D velocity components in the test tank is described.
    Źródło:
    Hydroacoustics; 1997, 1; 231-236
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Capabilities to use passive measurement systems to detect objects moving in a water region
    Autorzy:
    Mironiuk, Waldemar
    Buszman, Krystian
    Powiązania:
    https://bibliotekanauki.pl/articles/27322537.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    sea transport safety
    underwater observation system
    ship detection
    ship classification
    hydroacoustic parametrization
    bezpieczeństwo transportu morskiego
    system obserwacji podwodnej
    detekcja statku
    klasyfikacja statków
    parametryzacja hydroakustyczna
    Opis:
    The increase in the use of sea water is the basis for the development of the existing security systems in given areas. Monitoring the navigational situation in a given water area is one of the most important tasks aimed at ensuring the necessary level of safety in maritime traffic. Marine surveillance systems at sea are used for this purpose. As an interesting approach related to the study of the movement of vessels, this paper proposes a method based on the measurement of physical field disturbances generated by objects moving in the sea water. These disturbances can be referred to the upper (air space) and lower (underwater) hemisphere. In the upper hemisphere the motion of the object generates disturbances of the thermal field while in the lower hemisphere disturbances of the acoustic, hydrodynamic, magnetic, electric and seismic fields are generated. Detection of the floating objects and determination of movement parameters is realized mainly by active systems. There are radiolocation systems in the upper hemisphere (radar systems) and echo ranging systems in the lower hemisphere (sonars and echosounders). Monitoring of the upper hemisphere of sea vessels traffic is conducted in a comprehensive manner. The lower hemisphere is in the most cases omitted. Therefore, it is recommended to develop underwater observation systems as a source of additional information about floating objects and thus complement the existing systems used in navigation. However, at present, de spite the technological progress, there is a noticeable lack of the comprehensive solutions in the area of monitoring the vessels movement in the underwater space. Therefore, appropriate action should be taken to recognize this technology gap and increasing the safety of vessel traffic. The aim of the article was to present a fully passive, mobile underwater observation system that uses a number of sensors to monitor the underwater environment parameters, the research methodology and analysis of the obtained results. The method of deploying the measurement system at the selected geographical position and the measurement method are described. Based on obtained results, the analysis of sound pressure disturbances caused by passing ships was performed. A feature extraction method was developed to identify a passing vessel based on low frequency signal parameters.
    Źródło:
    Archives of Transport; 2023, 68, 4; 137--156
    0866-9546
    2300-8830
    Pojawia się w:
    Archives of Transport
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wykazanie możliwości stosowania urządzeń : sondy elektromagnetycznej (FLAT Model 801), hydroakustycznej (Son Tek, MicroADV) i urządzenia ADCP, do pomiarów rozkładów prędkości w warunkach laboratoryjnych
    Demonstration of the applicability of equipment : electromagnetic probe (FLAT Model 801), hydroacoustic (Son Tele MicroADV) and ADCP device for the measurement of velocity distributions in the laboratory
    Autorzy:
    Walczak, N.
    Hämmerling, M.
    Kałuża, T.
    Laks, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/270474.pdf
    Data publikacji:
    2013
    Wydawca:
    Centralny Ośrodek Badawczo-Rozwojowy Aparatury Badawczej i Dydaktycznej, COBRABiD
    Tematy:
    mierniki pomiaru prędkości
    badania laboratoryjne
    koryto hydrauliczne
    velocity measuring devices
    laboratory research
    hydraulic flume
    Opis:
    Celem badań było sprawdzenie dokładności uzyskanych wartości prędkości z wykorzystaniem laboratoryjnych i terenowych urządzeń pomiarowych. W pracy przeanalizowano wyniki uzyskane z dwóch urządzeń wykorzystywanych w badaniach terenowych. Pierwszym był przepływomierz elektromagnetyczny (FLAT Model 801), który działa na zasadzie prawa Faradaya. Jego zaletą jest brak części ruchomych, dzięki czemu pomiar nie jest obarczony błędami. Drugim przebadanym urządzeniem jest ADCP Stream Pro, który wykorzystuje występujące przy propagacji fali dźwiękowej zjawisko Dopplera, a mechanizm pomiaru polega na zmianie częstotliwości sygnału odbitego od poruszającego się obiektu. Uzyskane wyniki prędkości porównano z wynikami uzyskanymi laboratoryjną sondą hydroakustyczną (ADV), wykorzystującą zjawisko Dopplera. Sonda ADV przeznaczona jest do rejestrowania chwilowych składowych prędkości, ze stosunkowo dużą częstotliwością. Efektem pracy było wskazanie uniwersalności i ograniczeń urządzeń, które mogą jednocześnie pracować w terenie i w laboratorium.
    The aim of the research was assessing the precision of obtained velocity values with the use of laboratory and field measuring devices. The research analyses the results obtained with the use of two field measuring devices. One of them was the electromagnetic current meter (Flat Model 801), which operates on the basis of the Faraday’s law. Its advantage is the lack of moveable parts, thanks to which the measurement is not encumbered with error resulting from the mechanical nature of the propeller motion. The other field measuring device used in the research was the ADPC Stream Pro, which uses the Doppler Effect present in sound ware propagation. The measurement mechanism consist in changing the frequency of the signal reflected by the moving object. The obtained with the use by of the laboratory hydroacoustic (ADV), which uses the Doppler effect. The ADV probe registers components of the velocity vectors with a relatively high frequency. The research demonstrated the universality and limitation of the field measuring devices, which can operate both in the field and in the laboratory.
    Źródło:
    Aparatura Badawcza i Dydaktyczna; 2013, 18, 4; 341-348
    2392-1765
    Pojawia się w:
    Aparatura Badawcza i Dydaktyczna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-11 z 11

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