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  • Acoustical Society of America (ASA)  (4)
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  • Acoustical Society of America (ASA)  (4)
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  • 1
    Online-Ressource
    Online-Ressource
    Acoustical Society of America (ASA) ; 2008
    In:  The Journal of the Acoustical Society of America Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3188-3188
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3188-3188
    Kurzfassung: As the first German Director of the NATO Undersea Research Centre I was contemporary to the fall of the Berlin Wall in November 1989 and the unification of Germany in October 1990, the breathtaking termination of the Cold War without bloodshed. NATO's Undersea Research Centre, thirty years of age when the Berlin Wall fell, has been a key player and focal point of a most important and demanding field of defense research. It has been exemplary in combining customer oriented applied research on sonar concepts up to system demonstrators with basic research to understand, to model and to predict the variability of the ocean environment, the most difficult challenge of successful surveillance and reconnaissance. Some unique capabilities enable the Centre to serve the nations and the NATO commands: Above all, the ability to attract first class scientists to work together at the Centre for a few years and then return to their home countries, forming an ever growing international network of intense scientific cooperation. The advanced sea trial related technology and data treatment realized by a capable and flexible technical staff is no less decisive. The many high-ranking visitors, scientific, military and political underline the international standing of the Centre.
    Materialart: Online-Ressource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Sprache: Englisch
    Verlag: Acoustical Society of America (ASA)
    Publikationsdatum: 2008
    ZDB Id: 1461063-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Acoustical Society of America (ASA) ; 1999
    In:  The Journal of the Acoustical Society of America Vol. 105, No. 2_Supplement ( 1999-02-01), p. 1103-1103
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 105, No. 2_Supplement ( 1999-02-01), p. 1103-1103
    Kurzfassung: No more than six hydroacoustic receiver stations will be monitoring the three world oceans in the framework of the CTBT. Together with five T-wave stations they will synergetically cooperate with the seismic network which alone can neither provide the required accuracy of localization on the southern hemisphere nor the capability of reliable event discrimination of the oceans. To maintain the function of the sparse hydroacoustic network in case of an irretrievable station breakdown, an autonomous auxiliary unit for temporary replacement of fixed cable connected stations has been developed by FWG. The battery-supplied autonmous station, like the permanent stations, suspends the hydrophone at the depth of the SOFAR channel axis. The lightweight construction permits quick deployment and retrieval. The received acoustic signals are processed for prescreening at the station by algorithms with adjustable criteria to discriminate large explosions from natural events of similar energy turnover such as sea quakes and volcanic eruptions. The characteristics of the signals are transmitted by a surface buoy radio link via low orbit satellites to the data center, together with unprocessed, highly suspicious signals for expert analysis.
    Materialart: Online-Ressource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Sprache: Englisch
    Verlag: Acoustical Society of America (ASA)
    Publikationsdatum: 1999
    ZDB Id: 1461063-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Online-Ressource
    Online-Ressource
    Acoustical Society of America (ASA) ; 1984
    In:  The Journal of the Acoustical Society of America Vol. 75, No. 1 ( 1984-01-01), p. 173-185
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 75, No. 1 ( 1984-01-01), p. 173-185
    Kurzfassung: Contributions of environmental quantities related to the noise source field and the propagation path are derived from the comparison of measurements of the wind-dependent noise by omnidirectional receivers at a fixed North Sea station with shipborne measurements in the Baltic Sea. The influence of propagation loss on the wind-dependent shallow water noise appears to be only marginal, even at extremely different sea areas. The quantity governing the noise spectrum level under uncontaminated conditions is the wind speed at the sea surface for which the second power law relation has been verified between 50 Hz and 20 kHz and above a ‘‘threshold’’ wind speed of ≊5 kts. Neither the characteristic height of the sea waves nor the wind turbulence at the reference height are relevant to the noise production, but both may indicate wind profile changes which originate an essential portion of the noise variability for a given wind speed. Further deviations from the second power law are attributed to a bubble layer effect under storm conditions reducing or enhancing the high frequency noise level thus yielding a spread of the average spectrum level of more than 20 dB.
    Materialart: Online-Ressource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Sprache: Englisch
    Verlag: Acoustical Society of America (ASA)
    Publikationsdatum: 1984
    ZDB Id: 1461063-2
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
    Online-Ressource
    Acoustical Society of America (ASA) ; 1985
    In:  The Journal of the Acoustical Society of America Vol. 77, No. 4 ( 1985-04-01), p. 1409-1412
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 77, No. 4 ( 1985-04-01), p. 1409-1412
    Kurzfassung: Shallow water propagation measurements in the thermocline–halocline refractive sound channel of the Baltic Sea are utilized to estimate the absorption coefficient in low salinity water of 8 ppt (8.0 pH, 4 °C) for 0.5–10 kHz. The lower margin of the present data which are derived from transmission loss by subtraction of cylindrical spreading can be represented by the Francois and Garrison formula of 1982. However, measurements of the boron relaxation frequency indicate that this agreement does not necessarily support the assumed salinity dependence of the relaxation frequency but might be produced by appropriate scattering loss of the refractive channel.
    Materialart: Online-Ressource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Sprache: Englisch
    Verlag: Acoustical Society of America (ASA)
    Publikationsdatum: 1985
    ZDB Id: 1461063-2
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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