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OCEANS '93. Engineering in Harmony with Ocean. Proceedings

18-21 Oct. 1993

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Displaying Results 1 - 25 of 276
  • Passive damping to attenuate snap loading on a ROV umbilical cable

    Publication Year: 1993
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (90 KB)

    Summary form only given. Snap loading of the umbilical cable connecting a ship to a remotely operated vehicle (ROV) and its cage is a major problem when the ROV system is operating in rough sea conditions. Snap loading is the instantaneous, high magnitude, tensile loading of a cable. This loading arises when the amplitude and frequency of the ship motion is such that it causes parts of the cable t... View full abstract»

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  • Fuzzy min-max neural network based classification of underwater layered media due to attenuation effects

    Publication Year: 1993
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (59 KB)

    Summary form only given. A simple nonlinear structure for the implementation of underwater layered media modeling based on time delay in layers and exponential decay of the output signals' amplitude due to attenuation effects is proposed. The results of computerized simulation of this model are presented. A feed-forward fuzzy neural network classifier that uses min-max amplitude ranges to define c... View full abstract»

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  • An investigation of two body forces in a vortex wake

    Publication Year: 1993
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (59 KB)

    Summary form only given. Computer models and tow-tank trials are being used to study the roll behavior of a sonar twobody in two-part underwater twoing. Two-part two configurations, consisting of a depressor generating downforce on the main two cable to hold down a neutrally-buoyant connecting cable and twobody, are used to isolate towed devices from ship motion. However, during sea trials of one ... View full abstract»

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  • Fuzzy rule based depth controller for variable ballast system of autonomous underwater vehicles

    Publication Year: 1993
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (63 KB)

    Summary form only given. Variable ballast (VB) systems of autonomous underwater vehicles (AUV) are designed to compensate for changes in weights, variable loads, and displacement which occur during dive so as to keep submersibles at design condition such as neutral buoyancy and zero-trim. VB is also designed to create positive/negative buoyancy, so AW will ascend/descend to a desired depth. VB is ... View full abstract»

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  • Proceedings of OCEANS '93

    Publication Year: 1993
    Request permission for commercial reuse | PDF file iconPDF (985 KB)
    Freely Available from IEEE
  • Systematic search for multi-phase codes and design of mismatched filters for multi-user underwater sonar ranging system

    Publication Year: 1993, Page(s):I405 - I406 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (96 KB)

    Summary form only given. A technique is introduced to select poly-phase codes and design mismatched filters of a pulse compression system to have specific temporal and frequency response characteristics. In the particular problem under study, multiple sonar vehicles, up to eleven, need to be assigned codes and receiver filters that have nearly orthogonal signatures. Also, narrowband users that act... View full abstract»

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  • A PC based coherent sonar workstation for experimental underwater acoustics

    Publication Year: 1993, Page(s):III/359 - III/364 vol.3
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (610 KB)

    Apart from water, the most important component in an experimental underwater acoustics program is a versatile sonar system for transmitting, receiving, and recording acoustic waveforms. At the Underwater Research Lab (URL) at Simon Fraser University a simple yet fully coherent sonar workstation has been developed by making use of ZBM compatible personal computer (PC) technology, commercially avail... View full abstract»

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  • Real signals demodulation on a highly selective channel

    Publication Year: 1993
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (85 KB)

    Summary form only given. The underwater acoustic channel is probably one of the most complicated environments for data communication. The characteristics of this channel, which include fading, multipath and therefore frequency selectivity, Doppler shift preclude direct application of standard communications techniques. But there are many situations in which it would be desirable to have the means ... View full abstract»

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  • Computed tomography of biological structures in marine sediments

    Publication Year: 1993
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (32 KB)

    X-ray computed tomography (X-ray CT) images of a bioturbated sediment from the northern Gulf of Mexico continental shelf reveal clear evidence of two worm tubes, one circular and the other elliptical in plan view. Application of a segmentation technique using (CT number, gradient) feature space permitted a volumetric characterization of the tubes, which obtained results in good agreement with phys... View full abstract»

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  • Estimation of the composite roughness model parameters

    Publication Year: 1993, Page(s):I444 - I449 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (364 KB)

    The estimation of the environmental parameters of the Raleigh-Rice approximation of the composite roughness model and the parameters of the Kirchoff approximation for seafloor acoustic backscatter, given backscatter strength and bathymetric data, is investigated. Estimation of these parameters is an inverse problem whose solution gives surface properties from the measurements of the scattered fiel... View full abstract»

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  • Source localization using a non-traditional three-dimensional ocean modeler

    Publication Year: 1993, Page(s):II/224 - II/228 vol.2
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (364 KB)

    A real-time source localization system comprised of traditional signal processing and nontraditional artificial neural network technologies is presented. A technique for multiple receiver data fusion is also discussed along with issues regarding solution sensitivity and three dimensional contact state parameter estimation. This synergistic coupling of technologies provides scientists with a new to... View full abstract»

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  • High efficiency, reliable low frequency sound source for acoustical oceanography

    Publication Year: 1993, Page(s):I272 - I277 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    A new concept of at low frequency (below 1000 Hertz) underwater sound source has been developed and tested. The oscillation of a rigid body and an arrangement for converting a dipole oscillation of the rigid body to a monopole pulsation are used in this source. This arrangement allows the authors to generate practically unlimited displacement of the radiating surfaces without deformation of materi... View full abstract»

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  • Parameter estimation of random modulated chirp signals

    Publication Year: 1993, Page(s):I397 - I398 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (92 KB)

    Source or target tracking is an important problem in radar and sonar. If the target is moving with significant velocity, the received signal is nonstationary because of the time-varying delay. Usually the transmitted signal s(t) is narrowband with carrier frequency w, so that the delay does not distort the amplitude but affects only the carrier term. The signal received at the observation sensor i... View full abstract»

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  • Seismic penetrator technology for use in shallow water seismoacoustics

    Publication Year: 1993, Page(s):I450 - I454 vol.1
    Cited by:  Patents (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    In shallow water areas at very low frequencies (VLF), the sediments forming the upper part of the seafloor become an important part of the acoustic propagation path from source to receiver. It is difficult to fully understand the physics of propagation in this “extended wave guide” when we are limited to placing sensors only in the water. At the Naval Research Laboratory, two technolog... View full abstract»

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  • Passive localization using a spatially-referenced towed array

    Publication Year: 1993, Page(s):II/218 - II/223 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    We extend our work on the location estimation error performance of towed line array configurations of uniformly spaced passive hydrophones with emphasis on the spatially-referenced towed array (SPARTA). Using Cramer-Rao lower bound (CRLB) analysis as the means to compare the potential performance of different array configurations with spherical wavefront arrivals, we have previously shown that the... View full abstract»

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  • Pitch and yaw effects on very wide swath multibeam sonars

    Publication Year: 1993, Page(s):I353 - I358 vol.1
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    The first multibeam sonar systems, SASS and SEABEAM, offered stabilization for certain ship motions. Sass, a 1° system, incorporated pitch and roll stabilization as part of its original design in the early 1960s. In the mid-1970s, the first commercial multibeam system called SEABEAM followed the same stabilization concepts though its swath was narrower. Now, however, manufacturers are supplyin... View full abstract»

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  • A 300 Hz Janus-Helmholtz transducer for ocean acoustic tomography

    Publication Year: 1993, Page(s):I278 - I281 vol.1
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    Ocean acoustic tomography has need for low frequency and high efficiency transducers, in order to reach ranges greater than 500 km with large bandwidth and great depth capability. The characteristics of the Janus-Helmholtz transducer, designed by DCN Ingenierie Sud, widely answer these contradictory requirements. However, as acoustic tomography requires lower frequencies (a working frequency band ... View full abstract»

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  • A fuzzy logic based flight control system for “Ocean Voyager” autonomous underwater vehicle

    Publication Year: 1993
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (36 KB)

    A new variable structure fuzzy logic based flight control system (FCS) for the “Ocean Voyager” autonomous underwater vehicle is presented. This FCS is composed of three independently operating setpoint-based fuzzy logic controllers (FLCs) which regulate the heading, pitch, and depth of the vehicle. Each FLC contains a set of rules of the form: “IF <situation> THEN <actio... View full abstract»

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  • Short range position measurement systems for underwater vehicle dynamic positioning

    Publication Year: 1993, Page(s):II484 - II489 vol.2
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (444 KB)

    This paper presents a comparative study of position measurement systems for dynamic positioning (DP) of remotely operated underwater vehicles (ROV's) based on: speed logs, inertial navigation, long or short baseline acoustic systems, taut-wire and passive arm (PA). From this study, the PA was selected as the most adequate system for ROV DP when the tasks are to be performed only in a limited neigh... View full abstract»

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  • 3-D acoustic imaging with a thin lens

    Publication Year: 1993, Page(s):III444 - III449 vol.3
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    Too often, underwater video, photographic, and laser images are obscured by turbid water. Acoustic systems that are able to pass energy through turbid water typically generate images with insufficient resolution and contrast. This paper discusses an experiment that provided satisfactory images of objects at short range using acoustic energy at 3 MHz. The imaged objects had different shapes (cylind... View full abstract»

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  • Cloud masking for CoastWatch satellite imagery

    Publication Year: 1993, Page(s):II369 - II374 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    A cloud mask program is available for masking out all clouds present on CoastWatch satellite imagery products. CoastWatch satellite imagery are operational NOAA polar-satellite 1 km Advanced Very High Resolution Radiometer (AVHRR) data that are remapped for designated U.S. coastal regions. Sea surface temperature imagery is one of the current CoastWatch products; however, the product contains clou... View full abstract»

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  • Optimum detection of Weibull-distributed targets

    Publication Year: 1993, Page(s):II/5 - II/9 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    The backscattered power from an ocean-observing radar usually contains large, randomly spaced excursions often called sea spikes. These spikes can be considered as fluctuating targets embedded in a fluctuating background. The power returned from the fluctuating targets can be modeled as having a Weibull probability density function. The power from the fluctuating background can be modeled as an ex... View full abstract»

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  • Advances in multibeam echo sounder technology

    Publication Year: 1993, Page(s):I482 - I487 vol.1
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (388 KB)

    The SIMRAD EM family of multibeam echo sounders are characterized by extremely wide swath widths with up to 190° angular coverage, high accuracy due to interferometric bottom detection, integrated sonar imaging (sidescan), and ease of operation. Continuous improvements of these systems are being made as a result of user experience and new requirements. Examples of requirements which have recen... View full abstract»

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  • A neural network method for recognition of individual Orcinus orca based on their acoustic behaviour: phase 1

    Publication Year: 1993, Page(s):I455 - I457 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    Using a backpropagation neural network algorithm three experiments were designed to discriminate between the acoustic behaviour of Orcinus orca. The first experiment established the procedures by discriminating human vocalisations. The second and third experiments applied the procedures established in the first to the discrimination of Orca acoustic behaviour. Experiment two and three were designe... View full abstract»

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  • Wavenumber-frequency spectra of large-scale disturbances in the atmosphere and sea surface temperature in the mid-latitudes of the North Atlantic

    Publication Year: 1993, Page(s):II/213 - II/217 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (372 KB)

    Atmospheric pressure, surface air temperature and sea surface temperature (SST) data of the 22-yearly observations carried out by Weather Ships in the North Atlantic were used to estimate wavenumber-frequency spectrum of large scale variability in the atmosphere and upper ocean. Meridional constituents of pressure and temperature waves with wavelengths of 6000 km and 4000 km respectively were dete... View full abstract»

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